MASON, Ohio (AP) -- Juan Martin del Potro has reached the semifinals of the Western & Southern Open, which is still trying to catch up from the rain.

Del Potro beat France's Jeremy Chardy 6-1, 6-3 in the opening match Friday, reaching the tournament's semifinals for the first time. He won the bronze medal at the Olympics in London, then was knocked out in the first round of the Rogers Cup in Toronto last week.

Chardy got into the tournament as an injury replacement for John Isner, who has a sore back. He beat Andy Roddick and Andy Murray, becoming the first injury replacement to reach the quarterfinals of an ATP tournament this season.

Rain interfered with two singles matches Thursday night, postponing matches involving sixth-seeded Caroline Wozniacki and No. 9 Li Na.

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