Serena Williams' French Open is over after a first-round loss in mixed doubles to go with her quick exit in singles.

World number 10 John Isner beat defending champion Ryan Sweeting 7-6 (7/1), 7-6 (7/4) on Friday to reach the semi-finals of the $442,500 ATP US Men's Clay Court Championship.

Feliciano Lopez, ranked 15th in the world, won his Houston debut on Wednesday, beating Paolo Lorenzi 6-4, 7-6 (7/4) to reach the quarter-finals of the ATP Tour US Men's Clay Court Championship.

American Ryan Sweeting launched his title defence at the US Men's Clay Court Championship on Tuesday with a 6-3, 7-6 (8/6) victory over Brazilian qualifier Ricardo Mello.

Juan Martin del Potro fought off stomach problems and beat Ivo Karlovic on Friday, leaving Argentina tied with Croatia in the Davis Cup quarterfinals.

Argentina kept their Davis Cup final hopes alive on Saturday when David Nalbandian and Eduardo Schwank defeated Spain's Feliciano Lopez and Fernando Verdasco 6-4, 6-2, 6-3 to cut the deficit to 2-1.

Adrian Ungur pulled one back for Romania defeating Juan Monaco 6-4, 2-6, 6-3 but by then Argentina had already taken an unassailable 4-0 lead and progressed to the next round of the Davis Cup.

Eduardo Schwank was fined $1,000 for his erratic and unusual play after losing 6-1, 6-7 (5), 6-1 to fellow Argentine Juan Ignacio Chela in the second round of t