GAINESVILLE, Fla. - Antonio Morrison slumps down in an undersize office chair inside Florida's football facility. He kicks his legs out, and his left hand runs over his surgically repaired left knee covered by black sweatpants.

Morrison keeps that knee hidden but insists it's as normal as they come. It's hard to believe the 20-year-old senior linebacker appeared to have his football career gravely altered back in January, when his left knee was shredded during the Gators' bowl game.

But then you look at the film of the ruthless play that has haunted opposing offenses all season. You see the speed that jets him from sideline to sideline. You hear the bone-jarring hits. And you see the stats: 86 tackles with 11 for loss and 2.5 sacks in 12 uninterrupted starts.

You have to believe it, but hearing how Morrison got to an All-SEC-caliber season seems too fantastical. With every cut, sprint and tackle, Morrison defies medical science and human genetics.

"In all the years that I've done this, I've never quite encountered anything like this or someone like him," said Florida's director of rehabilitation Marty Huegel, who has been with the school for 35 years. "For lack of a better term, it's the most amazing thing I've ever seen."

***

East Carolina ran a screen. Morrison converged on the ball -- just like his coaches taught him -- but so did a defensive lineman. They dove from opposite directions to make the tackle, and the lineman crashed into Morrison's planted left knee.

Morrison collapsed, releasing blood-curdling screams that pierced the ears of a Birmingham Bowl crowd of 30,083 and echoed through television sets and radio stations carrying the broadcast.

"Everybody in the game could hear that," linebacker Jarrad Davis said, "almost like a silence came over the crowd when he screamed. It was hard to see and tough to hear."

"In all the years that I've done this, I've never quite encountered anything like this or someone like him. For lack of a better term, it's the most amazing thing I've ever seen." Florida's 35-year director of rehabilitation, Marty Huegel

Immediately, Morrison, lying on the damp turf at Legion Field, knew something was seriously wrong. Trainers gathered and Morrison was carted off.

Diagnosis: Multiple torn knee ligaments, including the ACL. A day later, Morrison wanted to start rehab.

"That's how I'm made. I'm not just going to sit around," Morrison said. "It ain't gonna get better with me just sitting around. I'm trying to get going and get myself better so I can get back on the field."

Before Morrison could go, he and Paul Silvestri, associate director of sports health for Florida's football team, discussed a detailed plan for how to attack an injury of this magnitude. Privately, Silvestri and Huegel, the primary trainers working with Morrison throughout his rehab, wondered if Morrison would ever fully recover. They just wanted him to walk normally again and eventually play with his kids later in life.

This was attempting to fix multiple different components of the knee for stability, rotation and power. Players who undergo perfect surgery and perfect rehab fail to come back from this, and the ones who do rarely make it back to the same pre-injury physical level.

At the earliest, Morrison was looking at possibly 10 months before maybe being truly ready to play. A two-year recovery was even possible. Sure, Minnesota Vikings running back Adrian Peterson valiantly returned from a similar injury, but he's a Hall of Famer and the ultimate outlier.

Still, they were going to push forward with Morrison, who never doubted a 2015 return.

Morrison would undergo two separate surgeries. The first was to repair the ligaments around the ACL on Jan. 9 (six days after the bowl). His knee would heal to an extent, but not fully, as the trainers worked to get flexibility back in his knee and have him walk somewhat normally before his second surgery six weeks later.

Florida coach Jim McElwain calls Antonio Morrison "the alpha dog" of a Florida team that surprised many by winning the SEC East. John Raoux/AP Photo

In that time, Morrison, who continuously beat his trainers to the rehab room for 5:30 a.m. sessions, crutches and all, would experience the only real pain and frustration of his rehab. That came from exercises to straighten and bend his leg. Simply flexing his thigh muscles to generate motion sent searing pain through Morrison's leg, and frustration mounted when he sometimes couldn't flare his muscles at all.

"You're sitting here straining your hardest, and it's not doing anything," Morrison said.

With a tireless work ethic, Morrison forced his trainers to push him further. He asked for more reps in rehab, and when he didn't get them, he'd sneak away and redo an entire day's work at home.

Trainers asked for 10 reps, he'd do 20. They'd try and slow him down, he went harder. Huegel and Silvestri had to be safe and not stress the tissue in his knee, but they also had to be creative and keep Morrison active.

"With [Morrison], you had to challenge him," Silvestri said. "You had to make him sweat, make him breathe hard. If he didn't feel like he was working hard, then he didn't feel like it was a good rehab."

A week before his second surgery on Feb. 23, Morrison walked normally without crutches.

After his second operation, Morrison was again anxious to work, but he had to restart the entire process. It was back to generating flexibly with him sitting on the end of a table and using his right leg to bend and straighten his left knee. He'd lie face down on a table hanging his legs over to straighten them and contract his thigh muscles. There were endless leg lifts, and when his motion returned to about 105 degrees, Morrison used a stationary bike before moving to light, low-resistant leg presses.

Again, Morrison was the first to arrive for sessions, would greet teammates group lifts in Florida's weight room and was still pressing for more reps, making sure to double everything each day.

"It's a real pleasure working with a guy like that," Silvestri said. "The want-to is there. The drive is there. This guy was relentless."

About seven weeks into rehab, Morrison started pool workouts to take stress off his knee and then gradually moved to the AlterG anti-gravity treadmill that reduced his weight by 70-80 percent while he ran.

Morrison surpassed his trainers' goals for him in just about every session, sometimes weeks ahead of schedule. He progressed at a terrifyingly rapid pace and four months after his second surgery, Morrison was sprinting ... at full speed. He was squatting 500 pounds. He was 20 pounds heavier and cutting and jumping with zero limitations.

"I can't put a finger on it, and there's no way to describe it scientifically, but he heals differently than most," Silvestri said. "He doesn't develop soreness. It's a different deal."

After a complete evaluation in early July, Huegel found Morrison's knee to be "stone-cold normal, if not better" in terms of motion, strength and his ability to jump; all the things necessary for Morrison to play football in August.

"That was sort of frightening," Huegel said.

Gators linebacker Antonio Morrison (3) is tied for the team lead with 86 tackles and has 11 tackles for loss (2.5 sacks). Kim Klement/USA TODAY Sports

It was scary because Huegel and Silvestri couldn't find a reason to keep Morrison from playing. First-year coach Jim McElwain didn't believe anyone could heal that quickly, so he had a conference call with Morrison, his father and the trainers to talk about easing Morrison into fall practice and the season while starting him on a strict, non-negotiable rep-count.

Morrison complied, but he didn't like it -- just like he didn't like wearing the knee brace strapped to him. He was ready to go without limitations.

"I only know one way, and that's go, man," Morrison said.

***

The football field is Morrison's domain, his sanctuary.

Growing up in Bellwood, Illinois, just 10 minutes from Chicago's crime-stricken South Side, Morrison learned to harness both aggression and restraint through football when he was 5. As he grew, so did the importance of football. Because of the rugged areas surrounding Morrison, it was hard to stay away from trouble and the occasional fight. But with football and help from his family, Morrison drifted away from the chaos to become a top recruit at Bolingbrook High School before signing with Florida.

Saturdays are now what Morrison lives for -- and why he was literally kicked out of Florida's football facility because of prolonged rehab sessions. It's why he skipped senior day festivities before the Florida State game last week in order to focus on the game itself.

Moments with his teammates are why he accelerated his rehab. The feel of another fall in Gainesville is why he yelled at his coaches when they tried to limit his practice reps in camp and why he's a voice of authority and focus in Florida's locker room.

Who Morrison is as a player and person is best described by the final play of Florida's 24-14 win over South Carolina. With three seconds remaining and Florida in drop coverage, Morrison sprinted across the field -- 43 yards away from the line-of-scrimmage -- to delivering a crushing hit on South Carolina's Pharoh Cooper to end the game.

"When we talk about the simplicity of 'win this down' ... he does that every single snap," McElwain said. "He's a throwback, man. He's the alpha dog."

Morrison withstood monumental odds and inspired those around him. McElwain says the story of No. 18 Florida's surprising 10-2 season is the story of Morrison's comeback. And he's right. Florida's run to the SEC championship game after five years of futility is about as improbable as Morrison's extraordinary story.

Morrison is leading the charge for this pack of Gators. He won't claim any responsibility for Florida's turnaround, but this program has felt the enormously positive effects from his unbelievable return.

"The intensity that he had during the offseason, it just can't be matched, and it carried over to the field," Davis said.