Yep, Robert De Niro and Sylvester Stallone play rival pugilists stepping back in the ring for one last fight. And yep, they starred in some other pretty famous boxing films. You don't have to remind director Peter Segal, who studied Raging Bull and the Rocky movies closely. ''I counted every punch in my [composition book],'' he says. (Rocky IV was the punchiest.) But Segal's sports comedy is more than a fantasy mash-up. ''It can be dismissed as a high-concept idea,'' he says, ''but there's a lot of heart.'' Enough for Warner Bros. to move the film from its original January 2014 release date to Christmas.