Roger Federer appears alongside Elmo in a new Super Bowl commercial for the running shoe brand, On, that has them debating ...

Roger Federer and Elmo from Sesame Street seem to disagree on the letters of the alphabet in a Super Bowl ad for ON running shoes.

Watch as Elmo sits in an umpire's chair and debates the two letters found on Federer's On-branded sneakers: Is it 'Q' and 'C' or 'O' and 'N'?