Top seed Justine Henin began her Australian Open campaign with an easy win over Aiko Nakamura.
Defending champion Williams also through - but Jankovic struggles
World number one Justine Henin has started her Australian Open campaign with a straightforward 6-2 6-2 win over Aiko Nakamura in Melbourne.
However, third-ranked Jelena Jankovic reached the second round the hard way, the Serbian needing over three hours to beat Austria's Tamira Paszek 2-6 6-2 12-10.
Despite serving six double faults and landing only 49 percent of her first serves, the Belgian top seed still proved far too strong for her unseeded opponent, Henin in the process extending her unbeaten run to 29 matches.
Henin claimed the opening set in 39 minutes, breaking Nakamura three times, serving three aces and hitting 15 winners.
The Japanese player threatened a comeback by breaking Henin in the first game of the second set and holding serve to lead 2-0.
But the Belgian stormed back, winning the next six games to close out the match in straight sets in 88 minutes.
Match points
In marked contrast, Jankovic, who came into the Grand Slam nursing a thigh injury, had to come from 4-1 down in the deciding set and saved three match points against 17-year-old Paszek.
There were eight successive breaks of serve in the final set as Paszek - who has cut her ranking from 365 to 42 in just two years - had five failed opportunities to serve out the match.
Afterwards Jankovic - whose day got off to a bad start when her driver took her to Albert Park (the venue for the Australian Grand Prix) instead of Melbourne Park - said she considered herself lucky to be in the second round.
"I was just trying to stay positive somehow and I found a way to win," she said.
"It was unbelievable when I was down those match points and I was really in some tough points and I was maybe lucky a few times. But a win is a win.
"I was actually praying and saying 'please God help me get out of the situation."
Defending champion Serena Williams made steadier progress into round two by beating newly naturalised Australian Jarmila Gajdosova 6-3 6-3.
Tough going
But 2006 champion Amelie Mauresmo found the going tougher - initially at least - against Tatiana Poutchek of Belarus, the Frenchwoman bouncing back from a first-set loss by winning 12 consecutive games to eventually take victory 6-7 (6/8) 6-0 6-0.
Other first round winners on day one included Australia's Jessica Moore, Romania's Edina Gallovits, China's Meng Yuan, Germany's Angelique Kerber, Russia's Olga Poutchkova, American Jill Craybas and France's Aravane Rezai.
Other seeded women to advance included Russian number 11 seed Elena Dementieva, 13th seeded Tatiana Golovin of France, Israel's number 17 seed Shahar Peer and number 26 seed Victoria Azarenka of Belarus.
