World number one Jelena Jankovic on Monday fired a warning to her rivals ahead of this month's Australian Open, saying she is fitter than ever as she continues her bid for Grand Slam glory.
The 23-year-old Serbian tops the bill at this week's Hong Kong World Team Challenge, which also features Wimbledon champion Venus Williams, as the players gear up for the year's opening Grand Slam.
Jankovic, who ended 2008 as number one after a see-saw battle for the top spot, has yet to win one of the four majors. Her best performance so far saw her lose in the final of the US Open last year.
"My main goal is to stay number one as long as possible and one of the priorities is to win a first Grand Slam," she said, adding that she was expecting to reap the rewards from her demanding off-season fitness regime.
"It gives me a lot more confidence because I know I have worked very hard," she said.
Jankovic, whose regime included high-altitude training in Mexico, said she was forced to run distances she had not attempted before, including a 10-kilometre (six-mile) effort.
"When my fitness trainer told me I had to run that much I thought I was going to stop in the middle but I was improving little by little," she said, adding that she had never been in better shape.
"I have never paid so much attention to being fit. Many people thought I was very fit because I look fit but in general I was never really fit and I always had problems when I had to play tough matches."
Jankovic said she was looking forward to getting on the courts in the World Team Challenge.
"I think it's a great opportunity to play many matches and to get my rhythm and get match fit. It's really great preparation for the Australian Open," she said.
The event, which runs from January 7-10, features four teams representing Europe, Russia, the Americas and Asia-Pacific.
The Australian Open starts on January 19.