Ena Shibahara and her American partner Asia Muhammad made a winning start in the women's doubles at the U.S. Open on Wednesday.

The ninth-seeded pair beat Russia's Varvara Gracheva and Poland's Katarzyna Piter 6-2, 6-1 on the third day of action at USTA Billie Jean King National Tennis Center, when Shibahara played in two events and won both.

Shibahara and Muhammad reached the final at the BNP Paribas Open in March, and went as far as the third round in both the French Open and Wimbledon.

On Wednesday, Shibahara also began her mixed doubles tournament with first-time partner Franko Skugor of Croatia, with the pair safely advancing to the second round of the year's final Grand Slam.

"I'm competing for the first time with my new partner," Shibahara said. "I thought I'd just have fun."

"The most important thing when pairing up with someone you've never played with is to find your groove together," she said.

Also in women's doubles, the all-Japanese team of Eri Hozumi and Makoto Ninomiya were eliminated in the round of 64.

The U.S. Open features a 128-player singles draw, 64-team doubles draw, and 32-team mixed doubles draw.