Naomi Osaka has defeated Jelena Ostapenko in straight sets at the U.S. Open for her first victory over a top-10 opponent in more than four years.

Coco Gauff held off four-time major champion Naomi Osaka 6-4, 6-4 on Thursday night to advance to the quarterfinals at the Mubadala Silicon Valley Classic.

LEXINGTON, Ky. Serena Williams was calm in a return more dramatic than some might have expected even after a long layoff. Williams needed to rally to win in her comeback following a six-month layoff, beating unseeded American Bernarda Pera 4-6, 6-4, 6-1 in Tuesday's first round of the Top Seed Open. Williams advanced to a second-round showdown against older sister Venus, who dispatched Victoria Azarenka 6-3, 6-2. The Croatian-born Pera eventually evened the set and had Williams down 0-40 at 4-4 before Williams, 38, rallied to stay on serve. She played really well.Williams needed another rally to win the next game before getting a hard-earned break to force a third set.