World number one Jelena Jankovic is working hard to get into shape for the 2009 season as she bids to break her Grand Slam duck at next month's Australian Open.

The Serbian won four titles this year and ends 2008 as the top player after a see-saw battle for the number one spot but has yet to win one of the four majors.

"I'm really training hard and doing my best to get as fit as possible. I hope to be ready and in the best shape ever by the Australian Open because my goal is to win," said Jankovic, speaking to reporters here by telephone from the United States.

The 23-year-old, back on the courts and in the gym after two weeks' holiday in Hawaii, reached the semifinals of last year's opening Grand Slam as well as the semifinal of the French Open and final of the US Open.

"I'm practising very hard to improve some of the sections of my game, to improve overall and to take my tennis game to the next level. I believe in myself and I believe my time will come," she said.

"I started training two weeks ago. I just came back from Mexico where I was in high altitude and the emphasis was on my fitness. I was doing a lot of running and spent a lot of hours in the gym trying to improve my strength and speed overall," she added.

"I'm trying to get very strong and fit for next year and to minimise my injuries as much as I can control."

As part of her build-up to the Australian Open, which starts on January 19, Jankovic is due to play in a new World Team Challenge in Hong Kong from January 7-10.

The event, also including Maria Sharapova and Venus Williams, will feature four teams representing Europe, Russia, the Americas and Asia-Pacific.