Angelique Kerber and Garbine Muguruza suffered shock losses in the second round of the BNP Paribas Open.
Australian Open champion Kerber went down to Denisa Allertova, while Muguruza was beaten by Christina McHale.
Seeds aplenty departed as Caroline Wozniacki and Sloane Stephens were also surprise losers at Indian Wells.
PLENTY OF SHOCKS
Kerber has struggled since her success at Melbourne Park, and that continued with a 7-5 7-5 loss to Czech Allertova.
Muguruza, the fourth seed, also struggled in a 7-5 6-1 loss at the hands of McHale, who had easily lost the previous meeting between the pair.
There was better news for Belinda Bencic, Victoria Azarenka, Sam Stosur and Ana Ivanovic as the quartet advanced.
Bencic and Stosur had three-set wins over Lauren Davis and Yanina Wickmayer respectively, while Azarenka cruised past Zarina Diyas.
Ivanovic was pushed before edging past Camila Giorgi 2-6 6-2 7-6 (7-5).
OTHER SEEDS DEPART
There were six seeded departures from the women's draw.
Joining Kerber and Muguruza were Wozniacki, who squandered a match point in her 4-6 7-6 (10-8) 7-5 loss to the in-form Zhang Shuai.
Eugenie Bouchard continued her good form with a 7-5 7-5 win over Sloane Stephens, while Anna Karolina Schmiedlova was crushed by Monica Puig 6-1 6-2.
Australian Daria Gavrilova, who had an impact at Melbourne Park, went down to Magdalena Rybarikova 2-6 7-5 6-4.
Roberta Vinci saved two match points in her 6-3 6-7 (7-9) 7-6 (7-5) win over Margarita Gasparyan, coming from 5-3 down in the final set against the Russian.
Elina Svitolina avoided an early exit, winning 12 of the last 15 games to overcome Annika Beck 4-6 7-6 (7-0) 6-1.
"We had some great points, really both going at it, and I was just a bit more aggressive," a pleased Bouchard said after her win.
After her 6-3 6-2 win over Diyas, 2012 champion Azarenka said: "I'm glad that I was able to go through this match."
SERENA BACK IN ACTION
Serena Williams takes centre stage once more on Sunday as the world number one meets Yulia Putintseva. Defending champion Simona Halep faces a tough clash against dangerous Russian Ekaterina Makarova, while Agnieszka Radwanska and Jelena Jankovic are also in action.