Agassi, Grosjean Win in Three for Quarterfinal Berths at Houston

"I threw up a couple of double faults at a bad time, leading 4-2 (in the third set)," Agassi said. "I got too aggressive. You don't finish off matches by trying to blast through somebody on clay. You've got to finish off by how you got there which is by discipline, shot selection and work ethic. I just lost concentration there."

Agassi will next face No. 6 seed Sebastien Grosjean, who also fought to a three-set win over a Spaniard in Oscar Hernandez.

Unseeded wildcard James Blake fell behind 2-4 in the first set before rolling out 10 of the next 11 games against France's Anthony Dupuis 6-4, 6-1.

"It's amazing what happens when you stop making errors," Blake said. "I didn't feel I was out of it at 4-2. I think he got down on himself a little at the start of the second set and that helped me."

Ecuadorian qualifier Nicolas Lapentti also advanced into the quarters with a straight-set win over American Kevin Kim.

Lining up Friday in quarterfinal action on the red clay are (3) Haas vs. (7) Jurgen Melzer (Tuna Melt leads career meetings 1-0), (1) Roddick vs. (8) Luis Horna (A-Rod leads 1-0 in tour play), (6) Sebastien Grosjean vs. (2) Agassi (Agassi leads 4-2, including the last three meetings), and (Q) N.Lapentti vs. (WC) Blake (American leads 1-0).