Houston - Top-seeded Nicolas Almagro of Spain overcame a slow start to beat Gael Monfils of France 2-6, 6-0, 6-3 on Thursday in the second round of the US Men's Clay Court Championships.
Second-seeded Tommy Haas of Germany faced Ricardas Berankis of Lithuania in a later second-round match.
Fourth-seeded Sam Querrey, the top ranked American at No 20 in the world, withdrew before his match against Rhyne Williams because of a strained right pectoral muscle. Fifth-seeded John Isner beat fellow American Jack Sock 7-5, 6-7 (3), 7-6 (3).
Monfils broke Almagro's serve in the fifth and seventh games of the opening set. Serving for the set in the eighth game, Monfils took a 40-love lead, then had consecutive double-faults before closing out the set on Almagro's service return error.
Almagro, ranked No 12 in the world, saved three break points in the opening game of the second set before holding his serve. He broke Monfils in the second game and took charge of the match.
Almagro broke Monfils in the eighth game of the third set with a leaping slam off Monfils's attempted lob. Almagro served a love game in the final game.
Isner broke Sock in the final game of the first set, and Sock won the final four points of the second set tiebreaker, including an ace at set point. In the third set, Sock had an ace to take a 3-2 lead in the tiebreaker, but Isner won the final five points to end the match.
Results on Thursday from the fourth day of the $455 775 ATP US Clay Court Championships (x denotes seeding):
Paolo Lorenzi (ITA x7) bt Flavio Cipolla (ITA) 7-6 (7/4), 6-1
Rhyne Williams (USA) bt Ivo Karlovic (CRO) 6-4, 6-7 (5/7), 7-6 (7/3)
Ruben Ramirez Hidalgo (ESP) bt Fernando Verdasco (ESP x6) 6-3, 6-2
John Isner (USA x5) bt Jack Sock (USA) 7-5, 6-7 (3/7), 7-6 (7/3)
Ricardas Berankis (LTU) bt Tommy Haas (GER x2) 6-3, 6-3
Nicolas Almagro (ESP x1) bt Gael Monfils (FRA) 2-6, 6-0, 6-3
Robby Ginepri (USA) bt Martin Alund (ARG) 6-2, 4-6, 6-4
Juan Monaco (ARG x3) bt Tim Smyczek (USA) 7-6 (7/5), 6-1