ISTANBUL: Li Na, the first Chinese player to win a Grand Slam singles title, added another famous first to her collection when she reached the semifinals of the WTA Championships with a 6-2, 6-1 rout of an ailing Victoria Azarenka on Friday.

It was the first time Li had qualified from the group stage of the tour’s flagship tournament, and there was rarely any doubt that she would do so with a success which avenged her narrow defeat to the Belarusian at the Australian Open final in January.

Azarenka suffered a lower back injury in the sixth game and required three lots of treatment and significantly impaired her movement.

However, Li had already been looking the sharper and more potent attacker, and had become the favorite to deliver her third win in three encounters and finish top of her group.

“I thought after the first set she would retire,” Li said of the injured Azarenka. “It was tough for me to focus all the time. But you never know what will happen.

“The first thing I thought after the first set is that she must retire. If I was feeling very bad I would have retired. If you keep playing you can make an injury worse.

“But when I saw what happened I said to myself ‘okay focus, and run for every shot’.” The result also ensured that Azarenka was eliminated and that Jelena Jankovic, the former world number one from Serbia, qualifies from the White Group in second place.

Jankovic will face Serena Williams in Saturday’s semifinals.

Serena Williams reached last four on Thursday night by brushing aside 2011 winner Petra Kvitova 6-2, 6-3 on Thursday to complete a clean sweep of her group matches.

She was intense, poised, rhythmical, and completely blinkered to thoughts outside the court.

Del Potro downs Baghdatis

In Basel, Switzerland, top-seeded Juan Martin del Potro of Argentina eased past Marcos Baghdatis of Cyprus 6-1, 6-2 in the Swiss Indoors second round on Thursday.

Del Potro forced two breaks of serve in each set and saved all five chances the 97th-ranked Baghdatis held in the first set.

In Friday’s quarterfinals, del Potro will face Paul-Henri Mathieu of France, who beat compatriot Michael Llodra 6-4, 6-3.

Five-time Basel champion Roger Federer is in the other half of the draw, and will face Grigor Dimitrov of Bulgaria on Friday.

The eighth-seeded Dimitrov, who won his first career title at Stockholm last weekend, won 6-3, 6-2 against Alexandr Dolgopolov of Ukraine.

All six second-round matches on Thursday were straight-sets victories.

Vasek Pospisil of Canada overcame big-serving Ivo Karlovic 6-3, 6-4 to earn a quarterfinal against another Croat, Ivan Dodig.

Edouard Roger-Vasselin of France beat German qualifier Tobias Kamke 7-5, 6-3, and will next play Daniel Brands of Germany, who beat Lukasz Kubot of Poland 6-2, 6-4. The winner is on course to meet del Potro in the semifinals.

Youzhny moved on to a semifinal against fellow Russian Dmitry Tursunov after he ousted Jeremy Chardy of France 6-3, 6-3.

Ferrer in last four

In Valencia, defending champion David Ferrer beat fifth-seeded Jerzy Janowicz of Poland 6-4, 4-6, 6-0 on Friday to advance to the semifinals of the Valencia Open.

The top-seeded Ferrer used his speed and ground game to overcome Janowicz’s powerful serve with key breaks to finish the first set and then start the third.

Ferrer will face the winner of the other quarterfinal between fellow former champion Nicolas Almagro and Fabio Fognini.

Also, Mikhail Youzhny outlasted Finland’s Jarkko Nieminen 7-5, 6-7 (4), 6-4 in 2 hours, 21 minutes.