Annacone, Federer's former coach: "There's no better challenge than beating Nadal".

Former Roger Federer coach between 2010 and 2013, Paul Annacone remembers how difficult it was to find the right tactics to hurt Rafael Nadal.

As a guest on the Inside-In Podcast, the American, now 61, spoke of the Spaniard's strengths: "I love challenges and contributing to a player's progression.

There's no better challenge than taking on one of the greatest athletes of all time, in all sports, like Rafa, and beating him," he says.

"I've been lucky enough to work with one of the most gifted players ever to hold a racket in his hands. It's a real contrast between the two.

It was fun to sit down and talk to Roger about what he needed to do to make Nadal feel uncomfortable on court.

In his tribute tweet, Roger said all the good things about him, about how he had helped him become a better player and love tennis even more.

Players love challenges. They don't see them as a disadvantage, but rather as something interesting to dig into.

That's what Roger had to do with Rafa. We've had over twenty years of excellence with these two guys," he concluded.