British number one Johanna Konta suffered a shock straight-set defeat by teenager Marketa Vondrousova in the second round at Indian Wells.
World number 11 Konta lost 7-6 (7-5) 6-4 to her Czech 54th-ranked opponent.
She failed to convert four set points in the first set and led 4-2 in the second against 18-year-old Vondrousova.
Konta, 26, has reached just one quarter-final in 2018 and only won eight matches since reaching the 2017 Wimbledon semi-finals.
She was erratic on serve against Vondrousova, landing only 51% of her first serves, and was broken in her opening two service games to fall 3-0 behind.