Lithuania's Ricardas Berankis beat second-seeded Tommy Haas of Germany 6-3, 6-3 on Thursday in the second round of the U.S. Men's Clay Court Championships.
Berankis, ranked 77th in the world, will face fifth-seeded John Isner, a 7-5, 6-7 (3), 7-6 (3) winner over fellow American Jack Sock.
Top-seeded Nicolas Almagro of Spain overcame a slow start to beat Gael Monfils of France 2-6, 6-0, 6-3.
Fourth-seeded Sam Querrey, the top American in the world at No. 20, withdrew before his match against Rhyne Williams because of a strained right pectoral muscle.
Berankis pressured Haas from the start and grabbed the momentum in the eighth game of the opening set when he rallied from consecutive double-faults and survived a break point to take a 5-3 lead. Berankis then broke the German's serve in the final game when Haas hit a drop shot into the net at break point.
Berankis broke Haas in the sixth game of the second set and won it in the ninth game when Haas fought off three match points before sailing a backhand wide to end the match.
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 12th, 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.