The fourth-seeded American committed 32 unforced errors while Voegele had four aces playing in windy conditions in the Southern California desert while Simona Halep, Ashleigh Barty, Garbine Muguruza and No. 22 Jelana Ostapenko moved on.
INDIAN WELLS, Calif. — Sloane Stephens lost to Stefanie Voegele of Switzerland 6-3, 6-0 in just over an hour Friday in the second round of the BNP Paribas Open.
The fourth-seeded American committed 32 unforced errors while Voegele had four aces playing in windy conditions in the Southern California desert. Voegele improved to 4-1 against the 2017 U.S. Open champion.
No. 2 seed Simona Halep beat Barbora Strycova 6-2, 6-4. Other seeded winners were: No. 12 Ashleigh Barty, No. 20 Garbine Muguruza, No. 22 Jelena Ostapenko, and No. 18 Qiang Wang.
Stephens wasn't the only seed to be ousted on the women's side.
No. 14 Daria Kasatkina, a finalist last year, lost to Marketa Vondrousova 6-2, 6-1; No. 19 Caroline Garcia lost to Jennifer Brady 6-3, 3-6, 6-0; No. 27 Su-Wei Hsieh was beaten by Johanna Konta 6-0, 6-2; and No. 29 Mihaela Buzarnescu lost to Daria Gavrilova 6-2, 6-2.
In men's opening-round matches, Steve Johnson beat fellow American Taylor Fritz 6-3, 6-3 and Stan Wawrinka edged Daniel Evans 6-7 (4), 6-3, 6-3. Also advancing were Feliciano Lopez and Hubert Hurkacz.
Novak Djokovic, the world's top-ranked player, won his first-round doubles match with Fabio Fognini. They beat Jeremy Chardy and Milos Raonic 7-6 (5), 6-1.