I found something interesting at tenniswarehouse.com. A thread on the Roddick vs Nadal 2004 US Open match. I was delighted to find a link to the highlights, because I've never seen the match before.
This was the first meeting between them. At the time Roddick was playing some of his best tennis and Nadal was years away from his prime, especially on the faster courts. Roddick destroys Nadal, then goes on to reach the quarter-finals where he lost an epic 5 set match to Joachim Johansson.
Roddick's game was at it's monsterous best right here. He started off serving in the 140-150 mph range, completely overwhelming Nadal with his raw power. Nadal was still in that defensive clay court mode. You can tell, he hasn't figured out how to deal with an aggressive baseliner on a fast surface. He looks completely out of sorts in this match.
Now compare it to the US Open quarters from last year.
This time the shoe is on the other foot. Roddick is the one getting beaten down. His serve and forehand have lost considerable power. To compensate for it, he decides to come in behind his serve and pressure Nadal into hitting passing shot winners. On the surface it's not a bad strategy, but the net has never been a particularly comfortable zone for Roddick. And Nadal is such a great player that you can't beat him with volleys unless you're able to keep him running. Andy knows that he can't out hit Nadal, so he tries to rush him into making mistakes. Unfortunately, it backfires and he loses in straight sets.
These videos demonstrate just how much their games have changed. Roddick and Nadal were both # 2 in the world and defending champions at the US Open. Makes you wonder who would win if the 2004 Andy met the 2011 Nadal on a hard court?