Indian wells - French Open champion Li Na, playing in her first event since pulling out of the Paris Indoor Open, exited the WTA Indian Wells event Wednesday, losing to 6-4, 6-2 to Angelique Kerber.
China's Li, the first Asian player to win a Grand Slam title, suffered her first loss to Germany's Kerber in four career meetings. All three previous contests were in 2010.
"A lot can change in two years," said Li, the eighth seed. "My serve didn't work. The three times I played her before I was getting points on my serve but today was different."
Kerber next faces world number one Victoria Azarenka, who dismantled Agnieszka Radwanska of Poland 6-0, 6-2.
Azarenka extended her season-long win streak to 21 matches as she raced into the semis.
The 30-year-old Li, from Wuhan, started her year off by reaching the final in Sydney and made it to the fourth round of the Australian Open before pulling out of the Paris tournament last month with a back injury.
Li held serve just once in the final set as the 24-year-old Kerber won the final six games of their night match on centre court at the Indian Wells Tennis Garden.
Li said the turning point was the sixth game of the second set. Trailing 3-2, Li had a golden opportunity to break Kerber as the German fell behind 0-40 on her serve.