Frenchman Sebastien Grosjean took advantage of Andre Agassi's serving troubles and snapped a string of seven straight losses to top-10 opponents Friday with a 4-6, 6-1, 6-2 upset in the quarterfinals of the US Men's Clay Court Championships.
Top-seeded Andy Roddick powered his way into the semifinals earlier Friday, closing a 6-4, 6-1 win over Luis Horna of Peru with four straight aces.
In the other quarterfinals, Austria's Jurgen Melzer eliminated defending champion Tommy Haas of Germany 2-6, 6-2, 6-4, and qualifier Nicolas Lapentti of Equador rallied to beat American James Blake 6-4, 1-6, 7-6 (3).
Melzer, in the tournament's final four for the second time in three years, will face Roddick in one of Saturday's semifinals.
Agassi struggled in his long three-set victory over Alex Calatrava on Thursday and his problems caught up with him against the relentless Grosjean, who took charge early in the second set and never allowed the No. 2 seed to get back in the match.
Agassi hit 49 percent of his first serves for the match.
With the score at 1-1 in the second set, Agassi won only four more points the rest of the set as the sixth-seeded Grosjean broke Agassi in the fourth and sixth games and again in the opening game of the third set.
"It was a good first set then he picked up his level and changed his strategy a little and started hitting it pretty high and pretty deep and I couldn't step up on it," Agassi said. "I made some bad decisions followed by some bad swings and the second set got away and I never got it back together after that.
"He started serving better and making his shots and put pressure on my serve."
Agassi rallied from triple break point to hold his serve in the fifth game. That's as far as Agassi's comeback got. Grosjean held and broke Agassi again in the seventh game.
Roddick hit 14 aces and 70 percent of his first serves in the match. He closed out a close first set by breaking Horna in the 10th game. Horna eluded one set point on Roddick's forehand error, but was done in by a drive by Roddick to the baseline.
Juan Carlos Ferrero extended his spring revival by beating French Open champion Gaston Gaudio 6-4, 4-6, 6-3 to reach the Open Seat Godo semifinals on Friday.
Ferrero broke second-seeded Gaudio at 4-3 in the deciding set, and held his nerve to reach his second semifinals in successive tournaments.
Until last week's Monte Carlo Masters, he hadn't reached the last four anywhere in a year, as he was curtailed by chicken pox and a wrist injury.
"I'm feeling very confident and getting a lot of matches," said Ferrero, the 2003 French Open champion.
"It's always tough against Gaudio, it felt like it was a final. We both played at a very high level. Since Australia I've been working very hard. I think I've been playing well for a while but you have to be patient."
In today's semis, he'll meet Russia's Nikolay Davydenko, who accounted for Belarus' Max Mirnyi 6-4, 6-4.