Jankovic has bragging rights now, spending the last two months atop the rankings despite a series of minor injuries and health issues last year. But the 23-year-old Serbian has her doubters because she has yet to win a Grand Slam tournament -- something that second-ranked American Serena Williams has done nine times -- and is short on match practice after becoming ill in Hong Kong.
"It will be an extra challenge for me," Jankovic said Saturday, two days before the season-opening major gets under way.
Still, she wasn't short on confidence, saying she feels she deserves the top ranking. She also undertook what she called her toughest-ever training regime in November and December, clearly adding some muscle, to help her stay on top.
"If I win a Grand Slam, it will be great result, great achievement," Jankovic said. "But I'm already No. 1, and I believe all of these girls here want to be where I am now.
"So I'm just enjoying it and really having fun. I play tennis because I like to play, not because I have to prove anything to everybody."
Williams, as usual, is also brimming with confidence.
"I would feel weird sitting here saying I'm not the best," said a relaxed and fit-looking Williams, who won the last Grand Slam, the U.S. Open, in September while briefly regaining the top ranking. "Even if I'm ranked 100 in the world, I would sit here and say I'm the best player.
"Nothing against Jankovic. She went out in the fall and worked hard and got the No. 1 ranking. I feel like I'm the best just because I'm not going to sit here and say anyone is better than me. I shouldn't be in tennis if I felt that way."
Both Williams and Jankovic would have to overcome some serious challenges to get to the Jan. 31 final. Even with the absence of defending champion Maria Sharapova -- still getting back to fitness after a shoulder injury sidelined her for most of the second half of 2008 -- the women's field shapes up as one of the strongest in years.
Russian Dinara Safina, earned the third seeding by winning four tournaments last year and reaching the French Open final and the U.S. Open semis.
No. 4 Elena Dementieva, the gold medallist at the Beijing Olympics, is on a 10-match winning streak.
-- The Associated Press