I think that no tennis player can truly be great unless they fear tennis balls. There are countless pictures of Roger and Rafa looking at tennis balls like they believe they are about to turn into monsters and eat them. Because of this they will do everything possible to make sure that tiny fuzzy yellow ball goes far far away and doesn't come back. This is why they are great.
( See? That is pure terror )However, recently, Roger's fear seems to have become slightly uncontrollable. He now believes that merely sending the balls far away is not going to save him, so instead, he flees
( RUN ROGER, IT'S GOING TO KILL YOU! )However, after some counciling, Roger seems to have faced his fear, and is now ready to embrace the tennis ball as a friend
( see? All good now )...ok, clearly not enough sleep, too much caffeine and too much staring at horribly dull articles for my dissertation have done weird things to my brain