b/c they are both aggresive players by nature (lub with his serve, fed with his groundstrokes) and thus, more suited to faster surfaces. generally the players who do well on clay are the ones w/o big weapons. with that being said, b/c they were both brought up on clay, they know how to play on it, unlike someone like roddick.
And then does Federer really have any favorite surface ?
I don't think clay is his least favorite surface, if he has any favorite.
As I understand, Federer's least favorite surface is indoor carpet.
He skips most of indoor season except ATP Master's final, as I know.
His 1st ever Master's series title was on clay at Hamberg.
I think he does pretty well on clay. He's just unfortunate to have
Nadal on clay since last year. And two years ago, he bumped
into Kuerten at FO.
Just some food for though, Ljubicic is terrible on grass. I was looking at his past on grass and he didn't get past rd of 64 in the 3 years I looked at at wimbeldon. And he didn't get past rd of 32 at Halle.
Before last year, Ljubicic was pretty terrible at every grand slam. He broke through last year with his solid fast-court and Davis Cup performances and now his increased confidence is taking him pretty deep into slams.
Look at Federer and Ljubicic. Clay isn't their best surface, but at least they can play well on it. This is the sign of their being raised on clay. Now look at the other end of the spectrum: Andy Roddick. The clay isn't his favorite surface and he wasn't raised on it either. The result: an absolute shocker if he were to reach anything past the third round.