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One of the last barriers of bigotry in all of professional sports will soon fall: Former Missouri star defensive end Michael Sam, an All-American and the SEC Defensive Player of the Year, has come out as gay.

Sam is expected to be a high-round draft pick in May, which would set a series of historic firsts in motion. He would be the first openly gay player drafted. Since most high-round picks make NFL rosters, he'd also likely be the first openly gay player in NFL history.

"I came to tell the world that I'm an openly, proud gay man," he told Chris Connelly of ESPN's Outside The Lines Sunday night.

“Michael has shown great courage in taking this step and not only do we support him, we are incredibly grateful. His decision to welcome us all into his world as he embarks upon a professional NFL career is an honorable one. This moment will resonate in a unique and important way for countless people, particularly LGBT youth,” said human rights activist Brendon Ayanbadejo, the former Baltimore Ravens player who has been advising Sam. Ayanbadejo is a member of the Athlete Ally Board of Directors, a group that fights homophobia in sports.

Sam's announcement sets up a number of difficult tests for the league, for Sam and for his fellow players.

For one, there will be a dizzying scouting combine, starting Feb. 19 in Indianapolis. Sam is expected to attend, and no draft prospect in the history of the combine has been dissected or discussed like he will be.

If Sam does attend, the combine will become one of the most heavily covered sports events in recent years because it would no longer be a sports-centric week of 40-yard dashes. It will be talked about across the media spectrum.

One general manager told Bleacher Report that Sam will be a true test of whether the NFL is actually open to all kinds of players. He believes that if Sam falls past the third round, then "something stinks. Because this guy is easily a high-rounder."

Bleacher Report NFL Draft Lead Writer Matt Miller agrees that Sam's talents should result in his getting picked in an early round.

"As a player, Michael Sam was one of the most impactful defenders in college football last season," Miller said. "Playing left defensive end, he was able to produce All-American numbers by using his quickness off the ball and high-level instincts. The tape shows a smaller pass-rusher with good agility, but (at 6'2", 255 pounds) he might struggle to find a true position in the NFL...The production and burst are easy to fall in love with, though. Teams needing an outside pass-rusher will like the tools he brings and his developmental potential as a player."

Sam will have to withstand being the center of attention outside and inside the locker room. And many believe his teammates may have a hard time playing alongside him.

"Half of the NFL's locker rooms will accept him and half won't. It's a roll of the dice whether he would be accepted or not," said one NFL player, speaking to Bleacher Report on the condition of anonymity.

The NFL will be watching. It released a statement saying: "We admire Michael Sam's honesty and courage. Michael is a football player. Any player with ability and determination can succeed in the NFL. We look forward to welcoming and supporting Michael Sam in 2014."

The NFL also reiterated it has a workplace conduct policy that prohibits discrimination of any kind. And a portion of the collective bargaining agreement states: "There will be no discrimination in any form against any player by the NFL, the Management Council, any Club or by the NFLPA because of race, religion, national origin, sexual orientation, or activity or lack of activity on behalf of the NFLPA."

However, with Sam in the NFL, the league and its players would be facing an unprecedented situation. The historic nature of this cannot be overstated.

An openly gay player in America's most popular sport has the potential to change a great deal all across the sports world. Gay NFL players—as well as players in other sports—have come out after they retired but never during their career, or, as Sam is doing, as their NFL career is beginning.

Sam's declaration has the potential to open other fronts on this issue as well. It can make current closeted NFL athletes less fearful. It could provide support to younger athletes, in high school or younger, that they don't have to deny their sexuality.

Sam told ESPN that he knew from a young age that he was gay.

"It shouldn't be a big problem" to people, Sam said.

"I want to be a football player in the NFL," he added.

When asked how he thought his future NFL teammates would feel, Sam said, "It shouldn't matter."

"I'm not afraid of who I am."

Sam told his college team in August he was gay. The team in turn not only had no problem with Sam's sexuality, they protected him. One Missouri player told Miller: "98 percent of the NFL could care less about someone being gay. It's the two percent that make us look bad."

The player added, "I got his back."

The reaction from NFL players, team executives and league officials queried by Bleacher Report in light of Sam's news was mostly positive but also cautious. Some of the players did not want to be identified out of fear of repercussions from the league.

What all agreed on was that Sam would face immense pressure. While he won't be the first openly gay player to try to make an NFL team, he will undoubtedly be the first to earn a roster spot, and most assuredly be the highest-profile player to do so.

If and when he is playing in the NFL, it will present a huge test of the NFL's belief that an openly gay player would suffer no discrimination in the sport. This is a belief that has been privately stated by some NFL officials for years. Yet other officials believed the league is still some three to five years away from being able to handle an openly gay player.

One player called Sam the "gay Jackie Robinson." Yes, that is pressure. (Though the better comparison might not be Robinson, but instead, Charles Follis, one of the NFL's first black players.)

The disagreement begins with the question of how Sam will be treated. While the one player believed "half of the NFL's locker rooms will accept him and half won't," another veteran player said Sam will be welcome in most locker rooms and will have few problems.

A third player explicitly said that he felt the player would face bigotry no matter what team he played for, because homophobia still is common in the NFL despite the league's best attempts to eliminate it. The player said Sam "would be targeted by players on the field and fans off of it."

"Just look at the Dolphins and (Richie) Incognito," said the player. Text messages between Incognito and Jonathan Martin featured repeated use of gay slurs. The player also pointed out what happened in Minnesota to former Vikings punter Chris Kluwe. Kluwe alleged he was released because of his outspokenness on gay issues and that his position coach repeatedly used gay slurs. The Vikings deny this.

Players also point to interviews done by the NFL Network's Andrea Kremer in which players state pessimism about how the first openly gay player would be treated.

Rogelio V. Solis/Associated Press

"There's such a stigma with gay and homosexuals within male sports," said Washington linebacker London Fletcher to Kremer. "It would be very difficult for that first person to come out."

New Orleans linebacker Jonathan Vilma told Kremer, "I think that he would not be accepted as much as we think he would be accepted, I don't want people to just naturally assume, like, 'Oh, we're all homophobic.' That's really not the case. Imagine if he's the guy next to me and, you know, I get dressed, naked, taking a shower, the whole nine, and it just so happens he looks at me. How am I supposed to respond?"

"That attitude is more prevalent in NFL locker rooms than you think," one of the players interviewed by Bleacher Report said.

The comments to the NFL Network follow the strong anti-gay remarks made by San Francisco 49er Chris Culliver at last year's Super Bowl. Also, at last year's combine, at least one team asked several players were asked if they liked women.

Team and league officials interviewed vehemently disagree that the NFL is homophobic. One team executive said Sam would be "the most protected player in NFL history" because neither the team he goes to nor the league itself would want anything to happen to Sam.

"Imagine how humiliated the league would be if the first openly gay player to be in the NFL suffered from extreme bigotry?," the team official said.

A league official said the NFL is ready for a gay player and that teams and players would treat Sam like any other player.

When Sam this past season was named the conference Defensive Player of the Year, he was the first player from the Missouri program to earn the honor since tackle Jeff Gaylord was Big Eight defensive player of the year in 1981. Sam doing the same about 35 years later was considered a great piece of history.

But that pales to what Sam has done now.