ISTANBUL — Samantha Stosur routed Li Na 6-1, 6-0 Friday to qualify for the semifinals of the WTA Championships.

ISTANBUL — Samantha Stosur routed Li Na 6-1, 6-0 Friday to qualify for the semifinals of the WTA Championships.

Stosur, the U.S. Open champion, dominated the French Open winner, dropping only the fifth game of the first set. She extended her career record against Li to 6-0.

Stosur joined Victoria Azarenka of Belarus in qualifying from the White Group.

Wimbledon champion Petra Kvitova had already secured her place in the semifinals from the Red Group before she beat Agnieszka Radwanska 7-6 (4), 6-3 Friday.

Radwanska's failure to win a set meant that Vera Zvonareva will join Kvitova in the semifinals.

Stosur said she wanted to redeem herself after losing 6-2, 6-2 to Azarenka on Wednesday.

"This was a really good turnaround from the match two nights ago," she said. "I played really well from start to finish."

Top-ranked Caroline Wozniacki was eliminated Thursday.

Li reached the Australian Open final in January and became the first Asian player to win a Grand Slam title when she won the French Open in June.