INDIAN WELLS, California (AFP) - Australian Open semi-finalist Jelena Jankovic reached the fourth round of the Pacific Life Open on Monday with a straight-sets win over Japanese veteran Ai Sugiyama.

Jankovic, ranked number four in the world and seeded third, encountered little resistance from Sugiyama in a 6-1, 6-1 victory and said her biggest concern was to maintain her focus in the breezy conditions.

"I really tried to do my job out there. I didn't want to let her get into the match," she said.

"Especially with the wind you cannot lose your concentration, because as soon as you do that you start making a lot of errors, and then you lose your rhythm," added Jankovic, who said her four double-faults in the second set were a direct result of the wind.

"I was tossing it, and I had a different toss every time," she said. "Also changing sides, the wind goes one direction, and at the other, obviously, the other way. But I was focused on the returns, so I could manage to finish the match."

The outgoing Jankovic, who took painkillers for a back injury in order to take the court against eventual champion Maria Sharapova in the Australian Open semis, said she was feeling well again and trying to get back to peak fitness.

"I'm healthy at the moment, and that's why you can see me smiling more on the court, compared to the beginning of the year, where I was not really being myself because I was hurt and I couldn't enjoy my game."

Jankovic's compatriot Ana Ivanovic, the top seed, headlined women's action Monday at the 5.7 million-dollar tournament that features both a WTA tier one draw and an ATP Masters Series event.

Ivanovic, whose runner-up finish to Maria Sharapova at the Australian Open propelled her to number two in the world, faces Italy's Tathiana Garbin.

Ivanovic, who like all 32 men's and women's seeds had a first-round bye, enjoyed a breakout season in 2007, with titles in Berlin, Los Angeles and Luxembourg.

France's Marion Bartoli, the sixth seed, took on German Angelique Kerber. Former world number one Lindsay Davenport, a two-time winner of this event, faced Taiwan's Chan Yung-Jan.

The 31-year-old American, who took nearly a year off the tour to have a baby, has won two titles already this year.

France's Richard Gasquet, the eighth seed, got the men's action off to a brisk start with a 6-2, 6-1 third-round victory over Argentina's Juan Ignacio Chela.

Defending champion Rafael Nadal of Spain, the second seed behind world number one Roger Federer, was the top men's seed in action, taking on US teenager Donald Young.

Third-seeded Nikolay Davydenko, the Australian Open champion, capped the night session against Germany's Philipp Kohlschreiber. Nadal won the first of his six 2007 titles at this event, defeating Djokovic in the final.