On the first play of the second half of the NFC Championship Game in 2011, Packers defensive end Ryan Pickett plowed into Bears right tackle J'Marcus Webb, who fell on the right foot of Bears center Olin Kreutz. The impact caused a tear of Kreutz's Lisfranc.

Kreutz went to the sideline and discussed the injury with team medical personnel. The Bears had a problem—there was no one else on the active roster who could effectively play center.

"Can you finish?" a coach asked Kreutz.

"Yeah, I can finish," he said. "But I can't block anybody."

So Kreutz finished the game. Then he spent six months in a walking boot.

Nobody outside of a small group of people ever knew anything about the injury.

This is the NFL. The mysterious injury/non-injury of Texans quarterback Tom Savage on Sunday may have gone viral, but it was not an isolated incident. It was a peek behind the curtain.

From the moment a player walks into a pop-up medical tent on the sideline and the doctor pulls down the zipper, he enters a secret injury world.

A player's name on an injury report? The tip of the iceberg.

Below the surface is where the real story is, where only a few can see it and understand its magnitude.

"Usually, the owner knows, the GM knows, the head coach knows, the position coach knows, and the doctor and the player," one former general manager says. "It's just that little circle—the people who need to know."

Injuries are a strategic card in NFL poker games, so teams and players hold them close to the vest.

Kreutz says when he had a sprained ankle, he'd downplay it and tape both ankles so the opponent wouldn't know which one was hurt. If the enemy knew, he says, they could figure out which blocks he couldn't make. And they also could try to attack the injury, which he admits he did as well when he knew an opponent had a specific injury.

M. SPENCER GREEN/Associated Press

Player agent David Canter says he has clients who are playing with injuries that should have ended their seasons. "One of them doesn't even show up on the injury report," he says.

"To be honest with you, injuries are minimized in the press," says Gordon Nuber, an orthopedist who worked for the Bears for 25 years until stepping down after the 2016 season. "But I don't think injuries get minimized from a care perspective."

Bengals offensive lineman Eric Winston, a 12-year NFL veteran who has also played for the Texans, Chiefs and Cardinals, says he has not been on a team that blatantly hides injuries that prevent players from playing. But he adds this: "There obviously are a ton of bumps and bruises and swollen knees, that sort of thing, that people don't know about."

Nuber, also a professor of clinical orthopedic surgery at Northwestern University Medical School, says how much information is made public often depends on the team's coach and his level of transparency.

Knowledge can be power on game days.

Panthers head coach Ron Rivera recalls preparing a special defensive package for an opponent's wide receiver combination when he was defensive coordinator of the Chargers. None of the opposing receivers were on the injury report that week. Then on game day, the primary wide receiver was not on the active roster.

"You spent your week preparing for the guy, and he doesn't play," Rivera says. "They got us pretty good."

The line between questionable and doubtful on the injury report can be, well, questionable. If the league suspects something is awry, NFL vice president of communications Michael Signora contacts the media relations director of the team in question. If the problem is not resolved, NFL vice president of player personnel Ken Fiore will talk to the team's general manager.

Teams can be fined for fudging the truth, but it hasn't gone that far since 2012, according to one league source.

The first question asked about an injured player usually is, "How long will he be out?" The answer usually is not clear.

"You never are quite sure about the length of time a player will miss on the front end," one team president says. "So people get nervous to describe an injury. A third-party doctor might say it's an eight-week injury, and then the player is ready to play in two weeks."

Take Colts quarterback Andrew Luck. He began the year on the physically unable to perform list. But team owner Jim Irsay said he expected Luck back early in the season. That didn't happen, and Luck went on season-ending injured reserve in November.

Stephen Brashear/Associated Press

"Every guy is different," Colts general manager Chris Ballard says. "You don't know how their bodies are going to react. Everybody takes best-case scenario. Drew Brees. Adrian Peterson. But not every guy is like that. You can't predict exactly when a guy will be back and ready to go."

And even if you could, you don't announce it. Not in the NFL.

On an NFL sideline, everything is out in the open. Except that which is not out in the open. Or that which is out in the open which is not recognized.

When Nuber began working for the Bears 25 years ago, two doctors and an internist worked games. Now, he says there may be a staff of 27 to 29 medical people on hand. Among them are numerous specialists, an airway management physician, an EMT crew, an X-ray technician, an opthamologist, a dentist, a spotter in the press box who has the power to stop the game and an independent neurologist.

The independent neurologist has been a welcome addition.

"I like having the independent spotter," one high-ranking front-office man says. "You don't want somebody working for the club making the call because in the heat of the moment, he could make a decision based on the outcome of the game instead of the best interests of the player—or the perception could be that he would do that."

The system still isn't perfect. Just because a neurologist is independent doesn't mean he can accurately diagnose a concussion on the sideline. The tests can be ambiguous.

And how independent can independent be when a doctor is in a crowd of nearly 100 people wearing the same colors? Independent neurologists have made questionable decisions this season involving Russell Wilson, Jacoby Brissett, Savage and others.

Sources say the NFLPA and NFL have had talks about trying to make the independent neurologist more accountable. If the union gets its way, the independent sideline doc will be required to make a call to the press box and sign off with another independent doctor in the press box before he can clear a player who is in the concussion protocol to return to the field.

Those doctors have a lot of help these days—from coaches and teammates of players who have been concussed, and from the players who have been concussed themselves. NFL spokesman Brian McCarthy says about 35 percent of concussions this season have been self-reported. That's up from 20 percent in 2016.

"You see less and less hiding symptoms," Raiders head coach Jack Del Rio says. "Guys are taking it seriously, and it's a healthy adjustment in the game."

Rivera says he has had both assistant coaches and players alert him to players who were exhibiting concussion symptoms. He says some players still fight about coming off the field.

"It's incumbent on all of us to help our buddies out," says Winston, who also is the president of the NFLPA. "I've done my share of, 'Hey, take a look at him. He doesn't look right to me.' Sometimes it's a serious issue. Sometimes it's minor and he just looks groggy. That's what doctors are there for, to check it out."

This season, the NFL implemented the use of pop-up medical tents on the sidelines. The tents are primarily for privacy, but they afford the additional benefit of slowing down the process. Only the doctor and the injured player are allowed in the tent.

"I don't think it's fair to have cameras in faces when guys might be hurt," Winston says. "There is a lot of emotion going on. There are a lot of TV doctors—people watching the game saying, 'He's fine.' Being out in public view can put the player in a bad position."

Del Rio says the tent worked the way it was supposed to in a recent game when two of his players were experiencing "stinger" symptoms. The players were checked out in the tent and given clearance to return to the game.

The athletic trainer's room is the nerve center for NFL injuries, and the team trainer knows more secrets than a Russian spy.

The trainer is the bridge between the injured player and the coach, the injured player and the team doctor, and the team doctor and the general manager. The relationships can put the trainer in difficult situations.

"I wouldn't want to be a trainer nowadays," says Dave Wannstedt, who coached in the NFL for 19 years and now is an analyst on Fox. "It's a tough job being a trainer. Once the trainer loses confidence in the locker room, he's not getting it back. You have to answer to the coach, the GM, the owner, the players, the doctors. Everybody can be pulling in different ways. It's not easy."

On some teams, trainers become player confidants. On others, there is a cool, professional distance.

"You have some very personable trainers," Winston says. "Some guys get along very well with trainers. And on other teams, they are there to do their job, and that's how it's treated."

On the day after a game, the trainer is a popular man. Winston says there are "tons of guys" in the trainer's room on a typical Monday, vying for time on the table or in the cold tub. Team trainers have sophisticated technology at their disposal, including hot lasers, cold lasers, ultrasound, cryotherapy and contrast techniques.

Ballard and GMs around the league typically spend two to three hours on a postgame morning dealing with injuries and their implications. "And after that, it never leaves my mind," he says.

On the morning after a game, Rivera purposely stays out of the trainer's room. He avoids seeing trainer Ryan Vermillion until after he does his press conference at around 12:30 p.m. This way, he doesn't have to try to explain diagnoses to the press while the team is still trying to figure out the severity of the injuries.

Phelan M. Ebenhack/Associated Press

After Rivera meets the press, he spends up to an hour with Vermillion discussing injured Panthers players. Sometimes, there is a follow-up meeting late in the afternoon. On Tuesday morning, he usually spends another 40 minutes or so with his trainer after most of the injured players have checked in and gone through treatments. On Tuesday afternoon, Vermillion meets with the whole coaching staff to map out the week ahead for injured players.

What happens in Vermillion's room can impact many fates.

Players and coaches aren't always in agreement on whether an injury is serious enough for a player to miss time.

When there is gray area, Rivera will talk it through with his player.

"Sometimes the player will tell me a little something different from what he tells the trainer," Rivera says. "Most of the guys don't want to let you down. They feel they let you down if they're hurt. ... I think they are more honest with the doctors than they are with the coaches and their teammates because they don't want to let us down."

Some players need to be told they can't play under any circumstances. Rivera recalls quarterback Cam Newton lobbying to play in the Panthers' 2014 season opener against the Buccaneers even though he had fractured a rib in a preseason game. Rivera told him he wasn't playing.

"He fought me, argued with me. He got mad and stormed out," Rivera says. "But I didn't play him. Come Sunday, he was cheering everybody on, helping Derek Anderson out. Then we won the game, and he was mad at me again. Sometimes you have to protect them from themselves."

Because of their insecurities, players often don't want to miss time. During the 2007 bye week, Kreutz had surgery to remove bone chips from his elbow. The next week, he taped up the elbow and played.

"You are always afraid to lose your damn job," Kreutz, who retired in 2011 after a 14-year career, says. "You create demons to keep going. My job was probably never in jeopardy, but you think that way, so you battle through things."

Kreutz's job was not on the line at the time, but many jobs are every week in the NFL. So, players sometimes don't even tell trainers and coaches about injuries.

Agent Blake Baratz has seen it. His take: "If you are a young guy on the fringes of the roster, you think, 'I'm banged up. Do I tell the trainer? If I tell him, they'll report it upstairs and put it in the file. They'll say I'm always in the training room. But if I don't tell them, how can I get healthy and play my best?'"

On the other end of the spectrum, some players need a little cajoling.

"Some guys you have to push because they don't know the difference between being hurt and having an injury," Rivera says. "We had a guy who tweaked his ankle. He came limping off. My instinct was to push this kid. Jog it off. Get ready to go back on defense. Put a little tape on it. You'll be OK. He ran back out there and played well. Knowing who he is, I felt I had to give him a little shove. We've had other guys, I look at them, based on who they are and how they react, and I know not to push them.

"As a rule, I don't question the player. From my perspective, nobody really knows how that player feels."

Del Rio takes a similar approach.

Ed Zurga/Associated Press

"You like to prop up an example like Charles Woodson, who finds a way to play despite incredible odds," he says. "That provides inspiration for others to try to follow suit. But to me the biggest thing is: Can the guy be effective? If they are in that iffy category, I try to talk with them directly and see what their mentality is. I don't want a guy on the field if he feels he can't protect himself and play well. ... I don't ever want to force a guy into doing something he's not comfortable doing."

Nuber, who worked with six head coaches, says he never had a team representative try to influence him to clear a player who wasn't ready.

"Most of the doctors in the NFL are the leading sports medical experts in the country," he says. "The guys I know wouldn't allow anybody to push them to make a medical judgement."

Winston says early in his career, he was aware of injured players getting pressured to play through injuries, but he rarely hears of it anymore.

Teammates also can be a source of pressure on the injured player. But Winston says he sees fewer side-eyes in the locker room about injuries than he once did.

When Bengals receiver A.J. Green missed a playoff game against the Colts in 2015 because of concussion symptoms, Winston didn't hear any of his teammates questioning him.

"There is so much more awareness in the league than there used to be," he says.

Player agent Mike McCartney was relaxing on a Sunday evening when he received a text from a client on the team flight returning from a game. He was feeling nauseous and light-headed.

"What do I do?" the player texted. "Go see the trainer," McCartney replied.

The incident speaks to the power of the agent in player health care. Agents have a lot of pull because players trust them. And players don't always feel the same about team representatives. In a 2013 NFLPA survey, the vast majority of players said they do not trust team doctors.

"Just because a doctor has taken a Hippocratic Oath doesn't mean he's not influenced by teams," Canter says. "Doctors aren't employees of players. I am. My priority is to protect my clients at all costs. The team's priority is to get the most out of the player for the least amount of money. At the end of the day for the team, it's just business. At the end of the day for me, it's my client's life."

To Winston, trust is on a case-by-case basis. Some players have implicit trust in team medical personnel. Others question everything. Trust can be affected by the player's personality, the people who are in his ear, his familiarity level with team medical personnel and the history of those care providers.

"You realize these doctors are working for the team," says Kreutz, who chose to have two surgeries during his career performed by physicians who didn't work for his team. "That's who they answer to. So I wouldn't say my relationship with them was always great."

As recently as 15 years ago, the practice of getting a second opinion on an injury by an independent doctor was taboo. It's now commonplace, and it seems to benefit all parties.

"Whenever a player gets hurt, whether it's something as simple as a sprained finger or as serious as a broken neck, the first step is I get the doctor's notes and images sent to an outside doctor for another opinion," Baratz says.

Canter has a team of specialists he trusts that can give him rapid second opinions.

"The player should have a right to get another opinion," Ballard says. "It's no different from what you and I would do. I would want to get more than one doctor's take with something major."

Winston says some team doctors are offended by players who look elsewhere for advice. Nuber was not one of them.

"If someone wanted to send their MRI to someone else, we felt that helped us and solidified our standing," he says. "We were always open to that—go anywhere you want to go. One guy they often went to would call us before he saw one of our players to see what we thought about the injury."

Winston says he has found the majority of the time, the team doctor's prognosis is confirmed. In the cases where there is conflict, a third opinion is sometimes called for.

"The thing you have to be careful of is eventually, you probably can find a guy who will say what you want him to say," Rivera says. "If the first two opinions are different, then getting a third makes sense. If the first two guys have the same opinion, why get a third? Are you looking for someone to agree with you? Then you cast doubt."

Sometimes players and their advisers seek more than just opinions from the outside. Baratz has a number of specialists he works with for treatments such as acupuncture, dry needling, massage and chiropractic. Some of his clients pay for these specialists to fly to their city regularly. He says Steelers linebacker James Harrison spends $300,000 a year on such treatments, and former Packers tight end Jermichael Finley was spending about $100,000 when he was playing.

Don Wright/Associated Press

"If you can get a couple of teammates on board, then you can split the cost of the flight, the hotel room and the session," Baratz says. "It's a tax write-off, and it's typically money well spent."

The agent sometimes will act as an advocate for his client on medical issues. An advocate may be more necessary for a fringe player than a star, according to McCartney.

He says when one of his clients who was on the bottom of his team's roster had surgery, the team didn't even call to see how it went.

"I've seen countless examples of teams never checking up on a guy no matter how severe the situation," he says. "Many players have to go through medical situations alone because they are not deemed important enough. When it's a star player, it can be quite different. There are no obstacles. It's complete cooperation."

Players who don't have leverage sometimes agree to contract clauses that can affect them when injured. Rookies who are drafted in the third round or later often are forced to accept a "split" contract. This means if the player goes on injured reserve, his game salary drops to a number far below the NFL minimum.

Other players agree to per-game roster bonuses. Both of the contract clauses are incentives for players to conceal injuries and play hurt.

"I know of a player with a severely dislocated arm and wrist," Canter says. "He's going to dress this weekend because he has a per-game roster bonus of $200,000. He should not be playing."

He won't be the only player out there who shouldn't be.

Not in the secret world of NFL injuries.

Dan Pompei covers the NFL for Bleacher Report. Follow him on Twitter: @danpompei.