Hingis, who had spent a total of 79 minutes on the court over the first two rounds, was slowed a little bit in the first set but closed out France's Virginie Razzano, 7-5, 6-1, in a little more than an hour.

Gunning for a fourth Australian Open title in five years, the top seed from Switzerland is one win away from a possible meeting with Williams, who dumped Tamarine Tanasurgarn, 6-1, 6-4, in 58 minutes.

Williams, the sixth-seeded American, will face either No. 9 Elena Dementieva of Russia or Daja Bedanova of the Czech Republic in the round of 16. Hingis plays Rita Grande of Italy.

Not to be outdone by her younger sister, Venus Williams needed just 51 minutes to dispatch Denisa Chladkova of the Czech Republic, 6-4, 6-1. The reigning Wimbledon and U.S. Open champion, who is in the same half of the draw as Serena Williams and Hingis, extended her winning streak on hard courts to 28 matches.

"I guess it is somewhat like two tournaments in which maybe the first week is possibly more dangerous because you're playing lower-ranked players until you're in the fourth round," Venus Williams said. "You really have to be on your guard. The second week is when you really have to be ready to play."

Also, No. 13 Amelie Mauresmo of France, the 1999 runner-up, recorded a 6-4, 6-2 victory over Iva Majoli of Croatia, who has battled injuries the last few years since winning the French Open in 1997. Mauresmo will play Venus Williams in the next round.

"I think that will definitely be an important match," Venus Williams said. "She likes playing here in Australia, I think she likes the surface and I think basically I want to go out there and play my game and be serious and not take anything for granted."

Seventh seeded Mary Pierce of France, the 1994 winner and reigning French Open champion was upset, 6-3, 6-2, by Paola Suarez of Argentina.

In the fourth round, Suarez will take on 10th seed and two-time semifinalist Amanda Coetzer of South Africa, a 6-2, 6-4 winner over Marlene Weingartner of Germany.

In men's action, fourth seed and 2000 semifinalist Magnus Norman of Sweden and fifth seed Yevgeny Kafelnikov of Russia were engaged in lengthy baseline duels in soaring temperatures, but both came on top.

Norman outlasted Alex Calatrava of Spain, 7-6 (7-2), 3-6, 7-6 (7-2), 6-3, and Kafelnikov, the 1999 champion and 2000 runner-up, overcame former NCAA champion Chris Woodruff of the United States, 6-7 (3-7), 7-5, 6-2, 6-3.

Swedish teen Andreas Vinciguerra ousted No. 10 Wayne Ferreira of South Africa, 6-0, 3-6, 6-4, 6-3, to reach his first Grand Slam fourth round.

Also, No. 15 Arnaud Clement of France topped former world junior champion Roger Federer of Switzerland, 7-6 (7-5), 6-4, 6-4, and No. 16 Sebastien Grosjean of France eliminated Thomas Johansson of Sweden, 6-4, 6-1, 6-4.

Hard-serving Greg Rusedski of Britain, fresh off his five-set elimination of top seed Gustvao Kuerten on Thursday, reached the round of 16 with a 6-1, 6-2, 6-1 rout of German qualifier Lars Burgsmuller.

After dropping just three games in her first two matches, Hingis lost twice that many Saturday as she vies for her first major since winning here in 1999. Last year she went without a Grand Slam singles title for the first time since 1996. Hingis was denied a fourth straight title in Melbourne with a loss to Lindsay Davenport in last year's final.

Hingis improved to 10-0 this season after helping Switzerland win the Hopman Cup in Perth and capturing the adidas International last week in Sydney.

Venus Williams has not lost a Grand Slam match since falling to Arantxa Sanchez-Vicario in the quarterfinals of the French Open. She has won 38 of her last 39 matches since that defeat.

Norman, who reached the final in Sydney last week, fired 15 aces with no double faults and hit 36 winners over the almost three hour match. The 24-year-old Swede has reached the fourth round of five of his last six Grand Slam events.

Kafelnikov, who needed five sets to overcome Germany's Nicolas Kiefer in the second round, was pushed again by Woodruff. The Russian was one game away from being in a two-sets-to-none hole but dug his way out and never looked back. He hit 58 winners compared to 34 for Woodruff, and countered 11 unforced errors with 10 aces.

"The conditions were quite difficult and obviously Chris had to play 100 percent to be in the match with me," said Kafelnikov, who is 6-1 lifetime against Wooddruff. "I think that's what he did up until the middle of the third set. I guess the fact is that he played a few tough matches in the beginning of the tournament, that played a huge role. He got quite a bit tired in the third and fourth set.

"I was feeling tired myself in that second set. Probably if I would have lost a set, I don't know what would happen. But I kind of hung in there and got the necessary break at 5-4 in the second set, and winning the second set was a huge relief. I knew that I was back in the match and my chances would come up."

Kafelnikov will play Vinciguerra next.

"I played him a couple of months ago in Stockholm Open and I have quite a bit of an idea what I need to do to get a victory," he said. "Having played him once before, I have an idea what exactly I need to do. I'm not going to expect an easy match. I'm going to prepare hard because that is already the stage in the tournament where everybody is playing well enough to get through to the fourth round."

An intriguing matchup features seventh seed Lleyton Hewitt of Australia taking on former world No. 1 Carlos Moya of Spain.

Hewitt survived a five-set encounter in the first round before rallying from big deficits in the first two rounds of his straight-sets win over Germany's Tommy Haas in the second round.

Moya, a runner-up here in 1997, has not dropped a set in his first two matches, including a victory over former world No. 1 Marcelo Rios in the first round.

Hewitt won his only meeting with Moya last year at Indian Wells, California in three sets.