Leatherheads
(2008)

In 1925 college football is more famous than pro football.

George Clooney resolves to save his pro team, the Duluth Bulldogs, from disbanding by recruiting a Princeton football player (John Krasinski) who is a war hero.  Rene Zellweger is a reporter who is assigned to expose the war hero as a fraud.  Clooney and Krasinski soon compete for Zellwegers affections.  Zellweger finally learns that Krasinski got credit for capturing a German platoon because 1.  he passed out drunk in his trench  2.  the Germans seized the trench without noticing him  3. when the battle woke him up he tried to surrender by saying in German "I surrender" which caused the Germans to all follow suit.  The fact that he was covered in mud was instrumental. 

Zellweger writes a great story but Kraskinski's agent (Jonathan Pryce) pays off a soldier to dispute the story and Krasinski stays a hero.  Krasinski defects to the Chicago team and a big game pits Clooney against Krasinski.  The Bulldogs are going to lose until inspired by Krasinski's war story, Clooney impersonates a Chicago player, intercepts a Hail Mary pass and wins the game.

Krasinski resolves to tell the truth and Clooney gets the girl.   

Thanks Don P!