12/10/2013 11:15 am ET | Updated Dec 10, 2013

Oscar Isaac Sings Katy Perry's 'Roar' Because He's The Best

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"Inside Llewyn Davis" star Oscar Isaac hit "Late Night With Jimmy Fallon" on Monday night with the eye of the tiger in tow. Isaac, who gives one of the year's best performances in the new film from brothers Joel and Ethan Coen, plays a folk singer in "Inside Llewyn Davis," and showed off his vocal chops by covering Katy Perry's "Roar" for Jimmy Fallon. Only as if it were a folk song. Must watch, etc. "Inside Llewyn Davis" is out in limited release now.


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