Beijing: World number one Jelena Jankovic pulled out of the Hong Kong World Team Challenge with a stomach ailment on Saturday, organisers said.

The 23-year-old Serbian’s Australian Open hopes hung in the balance after she was forced to withdraw from the exhibition tournament just nine days before the start of season’s opening Grand Slam.

“I have been weak and sick for the last couple of days,” Jankovic, a semi-finalist in Melbourne last year, told the crowd at Victoria Park Centre.

“I have been trying my best to get on the court but I feel slow, I have no reactions and it has been a struggle for me.

“My main goal now is to get back on court as soon as possible and get ready for the Australian. I will try and stay optimistic and hope for the best.”

Jankovic had been scheduled to play China’s Zheng Jie in a match between losing semi-finalists Team Europe and Team Asia Pacific when she pulled out.

The Australian Open warm-up tournament features four teams representing Europe, Russia, the Americas and Asia-Pacific.

World number six Venus Williams led Team America to victory by winning all three of her singles matches, including 6-2, 6-2 victories over Jankovic on Thursday and world number seven Vera Zvonareva of Russia on Saturday.

Williams dominated Russia’s Vera Zvonareva 6-2, 6-2 to give Team Americas a 3-1 victory over Russia and finish her only warm-up event before the Australian Open without dropping a set in singles play.

“It’s definitely a great way to start the year with wins against such talented players,” Williams said.