HOUSTON (AP) - Sixth-seeded Carlos Berlocq of Argentina overcame an injury to his left calf and surged past James Blake of the United States 6-4, 2-6, 6-1 in a first-round match at the U.S. men's clay court championship Monday night.

Berlocq took early charge with a 5-1 lead in the first set and then had to hold on to win the opening set. Blake easily won the second set with Berlocq getting his ailing calf wrapped before losing the final game of the second set.

Berlocq said he felt tightness in his left calf. He left the court briefly before the final set to get more treatment.

Sam Querrey of the United States, a 2010 finalist, beat Eric Prodon of France 6-1, 6-4 in another first-round match.

Defending champion Ryan Sweeting held off qualifier Ricardo Mello of Brazil 6-3, 7-6 (6). Sweeting is unseeded this year and his ranking has fallen from 93 at last year's event to 143.

In earlier opening-round matches, Igor Kunitsyn of Russia beat Xavier Malisse of Belgium 6-4, 6-2, Paolo Lorenzi of Italy beat Wayne Odesnik of the U.S. 6-7 (3), 6-2, 6-3 and Horacio Zeballos of Argentina bat Adrian Ungur of Romania 6-3, 6-3.

Former champion Tommy Haas withdrew with a right knee injury prior to a qualifying match.

Top-seeded Mardy Fish, who withdrew from Davis Cup play last week because of fatigue, has a bye into the second round and will play his first match on Thursday.

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