Roddick can challenge him as well if he serves big consistently for the entire match. If he does that, then he is tough to break even for a guy like Federer.
Roddick has good presence on the court and has so much adrenalin.
Safin, in his way, is very talented. It is a joy to watch them play; it is tennis of a very high quality.
But, then again, I had to stop because there was too much pain or too much trouble. After I retired I still had one more elbow surgery just to be able to do normal things.