Britain's Heather Watson lost 6-7 7-5 6-1 against Sloane Stephens of the United States in the first round of the Indian Wells Masters.
Watson, 29, took an early lead with a first-set tie-break and held her own in the second before Stephen took command.
The world number 73 then coasted in the deciding set to progress.
Elsewhere, Japan's Misaki Doi beat Ann Li in three sets while Yulia Putinseva came through in two against German Andrea Petkovic.
Romania's Irina-Camelia Begu won in straight sets against France's Fiona Ferro and Poland's Magda Linette beat Sweden's Rebecca Peterson in three.
Ukraine's Kateryna Kozlova saw off Ludmilla Samsonova of Russia in two with a second set tie-break.