[geoka9]

I would add burnout to the list of things that made Sampras retire. I would not include Roger Federer, because it's not like he's ever been Pete's nemesis - they've only played one match and it was a close one, but that's beside the point (Pete wasn't even ranked in the top 5 when he won his last US Open).

They are exactly one generation of players apart. Pete had been thoroughly burned out (and retired) long before Roger started to win everything in sight.

Agassi, on the other hand, became a philantropist closer to the end of his career and was trying to earn as much money for his foundation as he could. So he continued grinding despite his aggravating back problem (he had to get cortisone shots in his back before matches).