In the latest episode of Tennis Channel's "Coaching in the Bigs", Paul Annacone—the former coach of Roger Federer—caught up with Severin Luthi, one of Federer's current coaches and longtime partner on tour.

Federer underwent a second right knee surgery last June, and his return has been slower than fans prefer to see. But after training in Switzerland and Dubai over the off-seaon, he's began his comeback, going 1-2 before competing in Roland Garros.

Annacone asked what everyone would: what is Federer really like?

"He’s much maybe much funnier than people would think, that’s maybe first thing," Luthi said. "He’s really very funny and he’s also a very nice guy, OK people know that, but he really is that way."

The two coaches also marveled at how well Federer can bounce back from losses, crediting a great balance of work and home life.