Perth: Who will be more excited when they face off against each other – Roger Federer or Serena Williams?

The tennis superstars will play each other for the first time when Switzerland take on the US in the Hopman Cup mixed doubles on Tuesday.

Roger Federer in action for Switzerland at the Hopman Cup on Sunday. Credit:AAP

The match-up is set to draw worldwide interest, and the players themselves are just as excited.

Williams has already declared her intent to get a selfie with Federer to post on Instagram.