In men's tennis history, I think Sampras is still the best player ever at the moment, with Borg comes in second.

But with Federer, the guy has one of the best forehands ever. He can hit winners from everywhere: many of you must remember a stunning winner he hit against Agassi last year while running backward to chase down a ball that already passed him. He is also the best-ever to create seemingly impposible angles from both forehand and backhand. His down-the-line backhand is one of the best. His footwork and balance while on the run are considered by many to be the best. His return-game is probably under-rated: he has the ability to see the balls quicker than many can, and handle 130+ serve like a woman's serve.

But the best about Federer that I see is his ability to dissect his opponents prior-to and during a match: he would pick a style that hurts his opponents the most, and he has the ability to raise his level just enough to beat you: in this regard, he is really like Tiger Wood in golf. When you are so good, you're so confident that you sometimes just choose to play good enough to beat your opponents. That's the most scary part of his game that I see, and that's the reason why he doesn't really need a coach.