Caroline Wozniacki
Caroline Wozniacki of Denmark hits a return to Vera Zvonareva of Russia during their WTA tennis championships match in Istanbul, October 26, 2011. Reuters

Caroline Wozniacki celebrated in defeat on Wednesday after injured Russian Maria Sharapova's withdrawal from the season-ending WTA Championships made sure the Dane would end the year as world number one.

Wozniacki lost 6-2 4-6 6-3 to Russian Vera Zvonareva but with Sharapova already packing her bags for home, the loss in her second round-robin match in the Sinan Erdem Dome did nothing to weaken her grip on the top ranking she has enjoyed for 36 weeks.

World number two Sharapova, who began the day as the only player still able to topple the Dane in the rankings, quit after losing 7-6 6-4 to China's Li Na in the White Group.

Wozniacki, 21, now faces Wimbledon champion Petra Kvitova on Thursday needing victory to have a chance of reaching the semi-finals of the $4.9 million event.

Wednesday though was all about the rankings and she could shrug off the defeat to Zvonareva with a smile.

I like to play long matches, the world number one told reporters after a presentation by the WTA. I like to give the crowd a little bit for their money.

Five hours of tennis in two days, that's perfect. It's good conditioning. I need to keep in shape because when I go on holiday I probably won't do too much, added Wozniacki who beat close friend Agnieszka Radwanska in three sets on Tuesday.

GRAND SLAMS

Wozniacki, whose father and coach Piotr was urging his daughter on at the changeovers, said the number one ranking was just as important as winning grand slams -- a feat that has so far proved beyond her.

I think people do realize the true importance of it, she said. If you ask any little girl or any little boy, everyone will know what it means to be number one.

Maybe not everyone will understand what a grand slam (is) because you have to be into tennis to know that. If you're number one it means you've done something remarkable.

Wozniacki has spent all but one week as number one since last October, briefly losing it to Kim Clijsters in February.

While the Dane could bask in her achievement of finishing top of the rankings for the second consecutive year, Sharapova suffered a sad end to a season which propelled her back to the top of the game after shoulder surgery.

The ankle didn't recover as well as I had hoped after my first match, the former world number one told reporters.

It limits my movement a lot and it's not something I really want to risk. I tried to push it as much as I could but I think it was a little too soon.

Sharapova injured her ankle in Tokyo recently and only just recovered in time to compete in Istanbul. She will be replaced by first alternate Marion Bartoli of France who will face Victoria Azarenka on Friday.