NEW YORK (AP) — American Jack Sock retired from his first-round U.S. Open match because of a right calf injury.

Sock was trailing 6-4, 3-6, 6-1 to Pablo Andujar of Spain when he decided he couldn’t continue Tuesday. He said he strained the calf on a slide in the second set.

Sock hopes he can recover in time for doubles. He and Canada’s Vasek Pospisil won Wimbledon in their first tournament together, upsetting the 15-time Grand Slam champion Bryan brothers in the final.

The 21-year-old Sock had reached the third round at the past two U.S. Opens. He came in with a career-best ranking of No. 55.

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