Eugenie Bouchard made yet another early exit in a surprise loss at the BNP Paribas Open, while former champion Jelena Jankovic battled through.
For the third time in five tournaments in 2017, Bouchard bowed out in her opener, losing to Annika Beck in three sets at Indian Wells on Thursday.
Jankovic also went the distance, but the 2010 winner came out on top against Irina Falconi.
Lucie Safarova and Andrea Petkovic booked their spots in the second round at the WTA Premier event.
The Canadian started positively before suffering a 3-6 6-2 6-2 defeat to Beck.
Bouchard struggled in the deciding set, winning just five points on serve to be broken four times.
The first-round loss added to early exits in Brisbane and Acapulco this year.
JANKOVIC WINS THROUGH
It has been seven years since Jankovic won the title in California, but the Serbian showed some decent form in overcoming Falconi 6-2 3-6 6-3.
Jankovic, also runner-up in 2015, broke four times in the third set as both players struggled to hold serve.
Awaiting Jankovic in the second round is American great and 12th seed Venus Williams.
SAFAROVA, PETKOVIC UNTROUBLED
Safarova was somewhat wasteful against Lara Arruabarrena, converting just six of 17 break points, but the Czech still claimed a 6-3 6-2 win.
Petkovic had it far easier, spending just 43 minutes on court after Vania King retired when the German was leading 6-0 2-0.
Other players to progress on Thursday included Julia Goerges, Lauren Davis, wildcard Donna Vekic and qualifier Varvara Lepchenko.