Actor Jake Gyllenhaal stars in Southpaw, a new movie about a junior middleweight boxing champion who faces adversity. Scott Garfield/The Weinstein Company hide caption

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Jake Gyllenhaal plays boxer Billy Hope in Southpaw. Scott Garfield/The Weinstein Company hide caption

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Former Republican presidential nominee Mitt Romney and former heavyweight boxing champion Evander Holyfield face each other during an official weigh-in Thursday, ahead of their charity fight Friday. Rick Bowmer/AP hide caption

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Manny Pacquiao answers questions May 2 during a news conference following his welterweight title fight against Floyd Mayweather Jr. in Las Vegas. Pacquiao could face disciplinary action from Nevada boxing officials for failing to disclose a shoulder injury before the fight. John Locher/AP hide caption

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The MGM Grand marquee is reflected in an escalator with advertising for the Mayweather Pacquiao fight, which will take place Saturday in Las Vegas. John Locher/AP hide caption

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Julio Cesar Chavez at his home in Tijuana, Mexico. Carrie Kahn/NPR hide caption

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Floyd Mayweather Jr. (left) and Manny Pacquiao pose for photos after a news conference in Los Angeles. The two are scheduled to fight in Las Vegas on May 2. Jae C. Hong/AP hide caption

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Danny Trejo's big break came about partly because of a prison tattoo on his chest, depicting a woman wearing a sombrero. Thanks to that distinctive mark, a screenwriter recognized him as a champion boxer. Carlos Jasso/AP hide caption

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Rubin "Hurricane" Carter, the former boxer who spent years wrongfully incarcerated for murder, has died at age 76. his life inspired a Bob Dylan protest song and the film Hurricane, starring Denzel Washington. Paul Kane/Getty Images hide caption

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March 1, 1997: Hector "Macho" Camacho watches as "Sugar" Ray Leonard falls to the canvas during action in the fifth round of their fight. Charles Rex Arbogast /AP hide caption

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Angelo Dundee and boxer Cassius Clay (later Muhammad Ali), during a training session in 1966. George Freston/Fox Photos/Hulton Archive/Getty Images hide caption

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Joe Frazier (left) hits Muhammad Ali during the 15th round of their heavyweight title bout — the "Fight of the Century" — at New York's Madison Square Garden in March 1971. AP hide caption

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