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'?

Tim Henman faced Roger Federer, Rafael Nadal, and Novak Djokovic in their teenage years - and thought one of them wasn't ...

Roger Federer is a marketing powerhouse on his own, and it's best put in Nike's former tennis director Mike Nakajima's words ...

Rafael Nadal has equal admiration for Roger Federer and Novak Djokovic as the trio pushed each other to unprecedented heights ...

Alex de Minaur has lost in the Rotterdam Open final for the second year running, but won plenty of admirers as he pushed ...

Roger Federer will star alongside Elmo in a cheeky advert that will air during America's biggest sporting event.