MELBOURNE, Australia » Caroline Wozniacki advanced to the third round of the Australian Open with an emphatic 6-1, 6-0 win over American Vania King today as her first major atop the rankings continued to gather momentum.

The 20-year-old Danish player was never troubled in the 58-minute match, breaking the 88th-ranked King’s serve to finish it off and reach the third round for a 13th consecutive Grand Slam tournament. She has yet to win a major, but has held the No. 1 ranking since October and can retain it by reaching the semifinals here.

To get to the semis, she might have to beat seven-time Grand Slam winner Justine Henin, who continued her comeback from injury with a 6-1, 6-3 win over Elena Baltacha of Britain on center court.

The pair could meet in the quarterfinals. Henin will have to get through a tough match against two-time major winner Svetlana Kuznetsova just to get past the third round. The 23rd-seeded Kuznetsova beat Dutch qualifier Arantxa Rus 6-1, 6-4.

"I have a lot of good memories, almost all good memories, from Melbourne," said Henin, the 2004 Australian champion and runner-up here in 2006 and last year, when she was returning from a break from the tour.

Her comeback stalled after Wimbledon — she couldn’t play because of an elbow injury — and is making another return of sorts at Melbourne Park.

"I’ve been fighting hard the last few months and it’s great to be back in Australia."

Three women could finish the tournament at No. 1. Kim Clijsters and Vera Zvonareva are the others, and they opened with straight-sets first-round wins yesterday.

Clijsters had no charity for former No. 1-ranked Dinara Safina in a 6-0, 6-0 victory.

"I expect my opponent to come out and play their best tennis. She obviously didn’t do that," said Clijsters, who has won the U.S. Open twice since returning to the tour from a break to have a child. "But my attitude still was there to try and finish it off and not let her get back in the match."

The first-round match involving Lleyton Hewitt, Clijsters’ ex-fiance, was altogether different — a 4-hour, 48-minute, five-set loss to David Nalbandian that ended at 1:10 a.m. today.

Jo-Wilfred Tsonga, the 2008 Australian Open finalist, came back from two sets down for the first time in his career in another late five-setter.

Hewitt, a two-time major winner, usually revels in the late finish — he once beat Marcos Baghdatis in an Australian Open match not completed until 4:34 a.m. Nalbandian lost the 2002 Wimbledon final to Hewitt and the pair have a tense rivalry.

The Argentine drew begrudging applause from the parochial Rod Laver Arena crowd for his grit — he was a point from going two breaks down in the fourth; he wasted a chance to serve for the match in the fifth; saved two match points; then finished with a pinpoint lob as both players struggled with cramps and fatigue.

"What I take out of today? I take the brave heart that I put on the court," he said.

In 15 runs at the Australian Open, Hewitt’s best finish was his 2005 final defeat. He’ll be 30 next month. Australia hasn’t produced a homegrown winner of the national championship since Mark Edmondson in 1976. The drought isn’t likely to end soon.

Now all the talk in Melbourne will be about Rafael Nadal and his pursuit for a "Rafa Slam."

The Spaniard played only 11 games in his opening match yesterday, the match curtailed because of Marcos Daniel’s injured left knee. Not content to extend his Grand Slam string of 22 match wins with the 6-0, 5-0 scoreline, Nadal went to the practice courts to work on his serve. That’s the element of his game he thinks he needs to improve to become the first man in 41 years to hold all four majors at once.

Laver last did it in 1969, in a calendar year.