SAN JOSE (AFP) — Reigning Wimbledon champion Elena Rybakina of Kazakhstan lost to seventh seed Daria Kasatkina on Monday in a first-round match at the WTA San Jose hardcourt tournament.

World No. 12 Kasatkina won 11 of the last 12 games to win 1-6, 6-2, 6-0 in Rybakina's debut match since winning her first major title.

Kasatkina will next play American Taylor Townsend, who eliminated Australian Storm Sanders 6-1, 6-4 at the US Open hardcourt tuneup event.

After 23rd-ranked Rybakina rolled through the opening set in 35 minutes, Kasatkina dominated the final two.

American Madison Keys, the 2017 US Open runner-up, defeated China's Zhang Shuai 6-4, 6-2 to book a second-round date against Tunisian Ons Jabeur, who lost to Rybakina in last month's Wimbledon final.

Japan's Naomi Osaka, a four-time Grand Slam champion, and American sixth seed Coco Gauff would meet in a second-round matchup if both win their openers on Tuesday.

Former world No. 1 Osaka will face China's Zheng Qinwen while 18-year-old Gauff, this year's French Open runner-up, meets Anhelina Kalinina of Ukraine.

Osaka, whose ranking has slid to 41st, has not played since losing her first-round match at the French Open. She had suffered a right ankle injury in a tuneup event at Madrid.

Meanwhile, three-time Grand Slam champion Andy Murray of Britain crashed out in the opening round of the ATP and WTA Washington Open on Monday, falling to Sweden's Mikael Ymer.

The 35-year-old Scotsman fell to 115th-ranked Ymer 7-6 (10/8), 4-6, 6-1 after two hours and 50 minutes at the US Open tuneup tournament.

"I'm excited," said Ymer, who saved four set points in the first set.

"A lot left to do but it's a very good start of the American swing."

World No. 50 Murray, the 2012 and 2016 Olympic champion, is trying to earn a seeding at the US Open, which he won a decade ago.

"It's still possible," Murray said.

"I would just need to have a good run in Canada or Cincinnati really. It's pretty straightforward if I was to make a quarterfinal or a semifinal, which right now — after a loss like that — doesn't seem realistic."

"I do feel like if I play very well that I could do that. But I'll need to certainly play better than I did today."

Seven-time Grand Slam champion Venus Williams, playing her first singles match in nearly a year, was also eliminated in the opening round, falling to Canadian qualifier Rebecca Marino 4-6, 6-1, 6-4.
"It was nice to have the crowd behind me," Williams said.