British qualifier Katie Swan lost on her debut in the Indian Wells main draw after she was unable to take her chances against Spain's Cristina Bucsa.
Swan, who came through qualifying on her debut at the BNP Paribas Open, lost 7-6 (8-6) 7-5 to 90th-ranked Bucsa.
The British number six, ranked 156th in the world, could not convert a set point at 6-5 in the tie-break as Bucsa, 25, turned the opener in her favour.
Swan, 23, was twice a break up in the second and lost five set points at 5-4.
After Bucsa dug in to eventually hold serve for 5-5, the Spanish qualifier broke for 6-5 and served out the first-round match, with Swan seeming to struggle physically towards the end.