Djokovic, Wozniacki into China semis

Top seeds Caroline Wozniacki and Novak Djokovic powered into the China Open semifinals on Friday, while Chinese favorite Li Na battled to her best result ever in her home tournament.

Newly crowned world No. 1 Wozniacki pulled off the 7-6 (1), 6-3 win against Ana Ivanovic despite suffering a painful knee injury just after 90 minutes into the match at 3-1 in the second set.

With her knee heavily taped, the Dane returned to the court and fended off a late charge by Ivanovic to serve out the match.

Ivanovic fired in seven aces to her opponent’s one, but double faulted nine times and won only two break points against three for Wozniacki, who squandered another eight opportunities to break the Serb.

Defending champion Djokovic, ranked No. 2, fended off all seven break points he faced while breaking opponent Gilles Simon three times on his way to the 6-3, 6-2. It’s the fifth straight time he’s beaten the Frenchman.

"I’m very happy that my serve is getting better and better and hopefully, I’m going to use it more and more," Djokovic said.

The U.S. Open runner-up is enjoying a surge in form, crediting his semifinals appearance at Wimbledon with providing a boost in confidence. The semifinals here are his fourth in his last five tournaments.

Looking for his second title of the year, Djokovic will meet American qualifier John Isner, who upset fourth-seeded Nikolay Davydenko 7-6 (4), 6-4, serving 18 aces to the Russian’s one.

Djokovic beat Isner in their only previous match in March, but it took the Serb more than four hours and six match points to top Isner in Davis Cup play.

Li gave the Chinese crowd something to celebrate with a hard-fought 7-6 (8), 6-3 victory against Latvian qualifier Anastasija Sevastova to reach the tournament’s semifinals for the first time.

The world No. 15 struggled against her 55th-ranked opponent in the first set, winning on a tiebreaker. In the second, Li looked set to win at 5-2, but Sevastova broke her serve to stay in the game. Undeterred, Li promptly broke back for the win, eliciting a huge cheer from the home crowd at the Beijing Tennis Center.

"I wasn’t at all familiar with this opponent," Li said. "You see out on the court I was playing a little tight."

Second-seeded Vera Zvonareva made easy work of French Open champion Francesca Schiavone, winning 6-0, 6-2. That was one game better than the world No. 4 won against the Italian on the same court a year ago. Zvonareva improved to 10-0 against Schiavone in a match that lasted just 54 minutes.

"Not the match you expect from a Grand Slam winner," Zvonareva said. "I was really happy with the way I played and didn’t really give her a chance."

In the other women’s quarterfinal, Israeli Shahar Peer plays Switzerland’s Timea Bacsinszky later Friday.

David Ferrer of Spain downed Robin Soderling of Sweden 6-2, 6-4, and second-seeded Andy Murray was playing Ivan Ljubicic of Croatia in the evening’s last men’s quarterfinal.