Third-ranked Garbine Muguruza was upset by American qualifier Sachia Vickery 2-6, 7-5, 6-1 on Friday night at the BNP Paribas Open.
Muguruza took a 3-0 lead in the second set and appeared headed to the third round at Indian Wells, but the 22-year-old fought back. Vickery will face Naomi Osaka, who upset Aggie Radwanska after defeating Maria Sharapova in the first round.
Top-ranked Simona Halep beat Kristyna Pliskova 6-4, 6-4, and Petra Kvitova rallied past Yulia Putintseva 6-7 (4), 7-6 (3), 6-4 for her 14th consecutive match win.
Kvitova won the Qatar Open last month and has defeated six top-10 players this year.
Other second-round winners were No. 5 seed Karolina Pliskova, 7-6 (4), 6-1 over Irina-Camelia Begu; No. 6 Jelena Ostapenko stopped Belinda Bencic 6-4, 3-6, 6-1; No. 17 CoCo Vandeweghe defeated beat Kaia Kanepi 6-0, 7-6 (6); and Kristina Mladenovic edged Samantha Stosur 7-5, 7-5.
Nick Kyrgios withdrew Friday, citing a lingering elbow injury. He hasn't played an ATP match since losing to Grigor Dimitrov at the Australian Open. He'll be replaced by lucky loser Matteo Berrettini.
Serena Williams talks to media after defeating Zarina Diyas of Kazakhstan during the first round of the BNP Paribas Open tennis tournament at the Indian Wells Tennis Garden in Indian Wells, Calif., Thursday, March 8, 2018. (AP Photo/Crystal Chatham)
Williams sisters win to set up clash at Indian Wells
Serena Williams and sister Venus won at the BNP Paribas Open to set up a third-round clash in the desert tournament.
Serena got by No. 29 seed Kiki Bertens of the Netherlands 7-6 (5), 7-5 in the second round on Saturday in her return from a 14-month absence after giving birth to her first child. Venus preceded her younger sister on the stadium court and beat Sorana Cirstea of Romania 6-3, 6-4.
The sisters will resume their longtime rivalry on Monday. Serena leads Venus 17-11 all-time and has won eight of their last nine meetings, most recently the Australian Open final last year.
Serena Williams, of the United States, waves and leaves the court after defeating Zarina Diyas, of Kazakhstan, during the first round of the BNP Paribas Open tennis tournament in Indian Wells, Calif., Thursday, March 8, 2018. Williams won 7-5, 6-3, in her first match in more than a year. (AP Photo/Crystal Chatham)
It will be their earliest meeting since the sisters' first match in the series, a straight-sets victory by Venus in the second round of the 1998 Australian Open.
"Obviously, I wish it was anybody else in the draw, literally anybody, but that's OK," Serena said. "Just have to go out there and see how I am and do my best."
Roger Federer led Federico Delbonis of Argentina 6-3, 2-2 when their match was delayed by a heavy drizzle 56 minutes after it began.
Serena Williams, of the United States, reacts while playing Zarina Diyas, of Kazakhstan, during the first round of the BNP Paribas Open tennis tournament in Indian Wells, Calif., Thursday, March 8, 2018. (AP Photo/Crystal Chatham)
Wild card Danielle Collins defeated U.S. Open finalist Madison Keys 6-3, 7-6 (1) to continue a string of upsets.
Keys hasn't made it past the fourth round at Indian Wells in eight tries. The No. 15 seed was mistake-prone throughout the second-round match, committing five unforced errors in the tiebreaker.
Collins, ranked 116th and making her first appearance in the main draw, is just starting her second year on the WTA Tour.
Serena Williams, of the United States, hits a backhand to Zarina Diyas, of Kazakhstan, during the first round of the BNP Paribas Open tennis tournament in Indian Wells, Calif., Thursday, March 8, 2018. (AP Photo/Crystal Chatham)
She joined American upset winners Sachia Vickery, who beat No. 3 seed Garbine Muguruza; 16-year-old wild card Amanda Anisimova, who beat No. 23 seed Anastasia Pavlyuchenkova; and wild-card teenager Caroline Dolehide, a three-set winner over No. 30 Dominika Cibulkova on Friday.
In other matches Saturday, defending champion Elena Vesnina eliminated American CiCi Bellis 2-6, 6-1, 6-1; No. 4 seed Elina Svitolina beat Mona Barthel 6-4, 6-3; No. 12 Julia Goerges defeated Natalia Vikhlyantseva 6-4, 6-1; No. 27 Carla Suarez Navarro beat Su-Wei Hsieh 6-4, 2-6, 6-3; and No. 26 Daria Gavrilova dismissed Yanina Wickmayer 7-6 (3), 6-2.
Two seeded players lost: No. 18 Magdalena Rybarikova and No. 28 Anett Kontaveit.
On the men's side, No. 3 Grigor Dimitrov was upset by Fernando Verdasco 7-6 (4), 4-6, 6-3 and No. 16 Fabio Fognini went down against Jeremy Chardy 4-6, 7-6 (2), 6-4.
Fifth-seeded Dominic Thiem fired 10 aces to beat Stefanos Tsitsipas of Greece 6-2, 3-6, 6-3; No. 7 Kevin Anderson defeated Evgeny Donskoy 7-5, 6-4; and No. 12 Tomas Berdych rolled past German Maximilian Marterer 6-1, 6-4 in just over an hour.
No. 30 Pablo Cuevas beat Denis Shapovalov 7-6 (4), 6-3.