Li Na is banking on a strong performance at the China Open to reach this season's grand finale -- but she'll face tough competition from Maria Sharapova in a star-studded field with Serena Williams a late withdrawal.
Asia's top women's player has been a picture of inconsistency since winning the French Open last year, highlighted by last month's triumph in Cincinnati, which was followed by a third-round exit at the US Open two weeks later.
A last-16 defeat to Caroline Wozniacki at the Pan Pacific Open has left Li struggling to hang on to her eighth position in the race to reach October's WTA Championships in Istanbul, Turkey, featuring the season's top eight players.
"I'm now number eight, so it's very tough. Right now I don't know," said Li in Tokyo, when asked if she thought she would make it to Istanbul. "I think it will be decided after Beijing."
"I wish I can be in the championships, but I lost today, so the only chance is that I have to do well next week in Beijing," added the 30-year-old, who is yet to win the title in Beijing in front of her home fans.
Sharapova and world number one Victoria Azarenka travel to the Chinese capital with their places in Istanbul assured, on the back of a season when they have stamped their authority on women's tennis along with America's Williams.
The late withdrawal of the 2004 champion because of flu is a blow to organisers coming in a year when she has confirmed her place among the tennis greats by winning the Wimbledon, Olympic and US Open titles, raising her Grand Slam haul to 15.
Venus Williams, the elder sister and a former world number one, has also pulled out, citing a back injury, organisers said Friday.
Sharapova, the photogenic world number two from Russia, won her first Grand Slam title in four years at Roland Garros, while top-ranked Azarenka has claimed four trophies this year, including the Australian Open.
However, there are question marks over Azarenka's fitness after she pulled out of the Pan Pacific Open at the quarter-final stage, citing fatigue.
World number three Agnieszka Radwanska of Poland is defending her title after becoming the fourth player to qualify for the WTA finals.
"This is a goal for every player at the start of the season and I'm so happy to have made it," she said of the $4.9 million season climax.
And former world number one Wozniacki will be hoping to extend her recent revival, which included a first WTA title in more than 12 months in Seoul this month, by repeating her 2010 success in Beijing.
In the men's draw, Novak Djokovic can press his bid to beat Roger Federer to the year-end world number one slot when he defends an unbeaten record at the China Open, played at Olympic Green Tennis Centre.
The Serb has never lost at the ATP 500 event, winning on the two occasions he has entered, in 2009 and 2010. His path is smoothed by the absence of the rest of the "big four" -- Federer, Andy Murray and the injured Rafael Nadal.
Defending champion Tomas Berdych, who led the Czech Republic into the Davis Cup final earlier this month, is also not playing, with Djokovic's rivals shaping up as Spain's David Ferrer and Jo-Wilfried Tsonga of France.
"I was really disappointed that I couldn't play in Beijing last year because of my injury," said Djokovic.
Also expected in the men's draw are last year's losing finalist Marin Cilic of Croatia and France's Richard Gasquet.