Andre Agassi won his first-round match against Robby Ginepri in straight sets, but the two-time champion couldn’t have been pleased to lose his serve four times that night. A failure to serve his best proved the difference in a close semifinal against Juan Carlos Ferrero at last year’s U.S. Open; if Agassi is going to have a different result this year, he’ll need to fire a lot of first balls in the box.

So there was Agassi on Wednesday, working hard on his serve in an early afternoon practice session with coach Darren Cahill. By the look of his injury-shortened victory yesterday against 20-year-old German Florian Mayer, there is still room for a bit more improvement.

Mayer broke Agassi four times, including in the first game of the match. As he did against Ginepri, Agassi won 73% of points on his first serve. He got more first serves in yesterday, 57% compared to 54%, but did not fair as well on his second serve, which Mayer struck forcefully and with precision.

Agassi won only 49% of his second serve points before Mayer retired in the fourth set with a pulled muscle in his left leg, trailing 7-5, 2-6, 6-2, 1-0. Mayer got hurt in the first set, and the injury worsened as the match wore on.

“He’s an awkward player,” Agassi said of Mayer. “The way he delivers his backhand, you’re convinced he doesn’t have time to bring the racket head around and hit it cross-court, yet he can hit that thing like a fireball crosscourt. But sometimes when you have something ailing you, it gives you sort of a green light in your own mind to take any opportunity you get.”

Mayer said he felt like he had the shots to win if he had been at full strength.

“I played an unbelievable match in the second set,” he said. “If I had no injury, I think I had good chances to beat him today.”

While Agassi survived, Olympic silver medalist Mardy Fish, seeded no. 26, was upset in the second round by Michal Tabara of the Czech Republic, who is ranked no. 149 in the world. In the fifth set, Fish got into a few disputes over line calls that replays showed were good. He eventually lost 6-3, 3-6, 1-6, 6-3, 6-3. Fish has not performed well in Grand Slam tournaments, and yesterday he said he is beginning to wonder why.

“I’m starting to really think about it, to be honest with you,” he said. “This is the only thing that I’m missing.”

The match of the day was played over five hours and 9 minutes by Armenia’s Sargis Sargsian and Olympic gold medalist Nicolas Massu. Sargsian won the second-longest match in U.S. Open history, 6-7(6), 6-4, 3-6, 7-6(6), 6-4. He fought off cramps in the fifth set and looked on as Massu argued and kicked the umpire’s chair after he was penalized an entire game for slamming his racket on the court.