Andrea Petkovic set up a second round clash with Japanese giant-killer Naomi Osaka. Serena Williams and Agnieszka Radwanska now know who they play first - read on!
WTA Staff

STANFORD, CA, USA - A tantalizing second round match-up between Andrea Petkovic and Sam Stosur at the Bank Of The West Classic was spoiled on Monday, as Naomi Osaka - a 16-year-old Japanese qualifier playing in her very first WTA main draw match - rose up against Stosur.

Find out where you can watch live action from Stanford on WTA TV developed by Xerox!

Stosur, who was just one spot out of the seeds at the Premier-level event, had a match point at 7-6 in the second set tie-break and a 5-3 lead in the third set but succumbed in the end, 4-6, 7-6(7), 7-5.

Osaka's biggest win of the day may have come after the match in the press room, though - beginning with her answer to one reporter asking her if her win over Stosur was the best win of her life.

"It's probably the second-best win of my life," Osaka replied.

"The first being when I first beat my sister."

And then there was her answer to another reporter asking her if it was a coincidence that her last name is Osaka, and she was also born in the city of Osaka. "No, because everyone that was born in Osaka, their name is Osaka," she said, which was promptly followed by silence in the press room.

"I'm just joking, sorry!" she added. "It's just a coincidence!"

There was also a shout-out to her idol, Serena Williams - and, having come back from match point down to score the win over Stosur, she certainly emulated her favorite thing about the World No.1.

"She's everything," Osaka said of Williams. "I just like how she's down and can come back and win. You never know what's going to happen. I saw her in the player's lounge and I was like, 'Oh my God.'"

Another Top 20 player awaits Osaka in the next round. The No.8-seeded Petkovic held up her end of the bargain, twice rallying from a break down in the second set to beat Ajla Tomljanovic, 6-1, 6-4.

"I'm very happy, especially because I lost to Ajla the last time we played in a tough match," Petkovic said. "I just think she has so much raw talent and such a great future. I'm very happy I'm through."

The first opponents of the Top 2 seeds - Serena Williams and Agnieszka Radwanska - are also known now, after Karolina Pliskova took out Kimiko Date-Krumm, 6-1, 6-3, and Varvara Lepchenko beat Caroline Garcia, 6-4, 6-3. Pliskova will take on the No.1-seeded Williams (a first-time meeting) while Lepchenko will face the No.2-seeded Radwanska (Radwanska leads their head-to-head, 5-0).

Rounding out the winners were two young Americans, CoCo Vandeweghe and Sachia Vickery.

The last six first round matches will take place on Tuesday, including No.6 seed and defending champion Dominika Cibulkova taking on Garbiñe Muguruza, No.5 seed Ana Ivanovic facing Sabine Lisicki, and two-time Bank Of The West Classic champion Venus Williams playing Paula Kania.