INDIAN WELLS (AFP) - World number one Simona Halep and fifth seed Karolina Pliskova eased through their WTA Indian Wells openers on Friday but reigning Wimbledon champ Garbine Muguruza bit the dust in the California desert.
Halep beat Karolina's sister Kristyna Pliskova 6-4, 6-4 while Karolina eased past Irina-Camelia Begu 7-6 (7/4), 6-1 to reach the third round of the combined WTA/ATP hardcourt tournament.
Muguruza became the first major casualty of the event, suffering a shock 2-6, 7-5, 6-1 defeat to world number 100 Sachia Vickery.
"It slipped away a little bit from me," said Muguruza. "I'm going to learn a lot from this match. I'm going to watch it and I'm going to see what went wrong."
Muguruza, who was seeded third here, was named WTA player of the year last year after winning titles in Wimbledon and Cincinnati.
The 24-year-old also reached number one in the world in September and was ranked third heading into Indian Wells. This is the Spaniard's first loss to a player ranked in the 100s since she was beaten by Jana Cepelova (124) at Wimbledon in 2016.
Muguruza had five double faults and had her serve broken five times in the two-hour, 11 minute night match.
Crowd favourite Vickery posted her first career win over a top 10 player as she served masterfully and controlled the rallies with her ground strokes. Vickery said the partisan crowd motivated her.
"The atmosphere really helped me even though I was feeling it a bit physically. I kept telling myself 'just do your best'," said the 22-year-old, who is making her second appearance in Indian Wells.
Halep roared into the third round by overpowering Kristyna in straight sets. The 26-year-old Romanian will meet US wildcard Caroline Dolehide who beat Dominika Cibulkova, of Slovakia, 5-7, 6-3, 6-4.
"I was ready to play. I was ready to work and ready to fight," Halep said. "It wasn't an easy match. But I am really happy I won my first match here and I get a chance to play again."
Halep and Caroline Wozniacki have been taking turns at No. 1 this year. Denmark's Wozniacki took the world number one ranking after beating Halep in three sets in the Australian Open final, but Halep reclaimed it from her just prior to Indian Wells.
Wozniacki will play her first match of the tournament on Saturday against qualifier Lara Arruabarrena.
Halep won three out of the final four games in the second set, claiming victory when her opponent sailed a forehand long on the first match point.
Fifth-ranked Karolina Pliskova smashed four aces and won 76 percent of her first serve points in her 92 minute victory over Begu.
The Czech, who turns 26 on March 22, is hoping to improve on her semi-final finish here in 2017, part of a stellar campaign that saw her win titles in Brisbane, Doha, and Eastbourne and rise as high as number one in the world last July.
Elsewhere, ninth seeded Petra Kvitova won her 14th straight match to equal the longest winning streak of her career by outlasting Yulia Putintseva 6-7 (4/7), 7-6 (7/3), 6-4.
Rising star Jelena Ostapenko battled her way into the third round by outlasting Swiss Belinda Bencic 6-4, 3-6, 6-1.
The 20-year-old reigning French Open champion will next face Petra Martic of Croatia who beat Czech 26th seed Barbora Strycova 7-5, 6-4.
Ostapenko, of Latvia, beat Halep in last year's French Open final in three sets, becoming the lowest ranked and first unseeded player in history to win at Roland Garros.