MELBOURNE, Australia - Venus Williams lost to Alicia Molik of Australia 7-5, 7-6 (3) Monday in the fourth round of the Australian Open, extending her Grand Slam drought and keeping her from joining sister Serena in the quarterfinals.

Williams was seeking her fifth Grand Slam title and first since winning the 2001 U.S. Open. She reached five finals after that, but hasn't made it past the quarterfinals of a major since injuring an abdominal muscle in mid-2003.

Molik, the Olympic bronze medalist last year in Athens, will face No. 1 seed and 2000 champion Lindsay Davenport, who polished off Karolina Sprem 6-2, 6-2 earlier Monday. It's the first time that Molik, who stretched her winning streak to 12 matches, has reached the quarterfinals of a Grand Slam.

She broke the eighth-seeded Williams at love to finish off the first set, then fought off five break points in the second.

Both players held to force a tiebreaker, where Molik showed her best, jumping to a 4-0 lead, then falling again on a running forehand that she netted. She shook it off and finished off the match when Williams weakly hit a forehand into the net.

Molik refused to wilt under Williams' power attack, firing seven aces and other winners that kissed the lines.

"I think the key (was) I wasn't ever going to win the match waiting for Venus to make mistakes," Molik said.

Molik became the first Australian woman to reach the quarters since Anne Minter 17 years ago. Fellow Aussie Lleyton Hewitt also advanced Monday, overcoming a sore right hip to beat unseeded Rafael Nadal 7-5, 3-6, 1-6, 7-6 (3), 6-2 victory.

Trying to finish points quickly to limit his movement, Hewitt committed five consecutive errors in the fourth set after going ahead 0-40 while holding a 3-2 lead.

He then proved that he deserved his reputation as a battler. Hewitt got to a tiebreaker and won it, punctuating the points with his trademark fist pumps and shouts of "Come on!"

That got the fans roaring and left the 18-year-old Nadal shaking his head.

Being pushed to five sets seemed to take some of the steam out of Nadal. He asked for a massage on his left thigh after Hewitt broke twice and ran off a 3-0 lead in the deciding fifth set.

While serving for the match at 5-2, Hewitt had a double-fault and two unforced errors to give Nadal a pair of break points. He fought back to deuce, double-faulted on his first match point and squandered a second, then finished with an ace and a backhand from Nadal that sailed just long after a lengthy rally.

Hewitt dropped to his knees in celebration as the crowd roared.

"This crowd is second to none," said Hewitt, who also rallied for Davis Cup victories on the same court. "I was hurting a little bit in the third set. You try to get all of the negative thoughts out of your mind."

Hewitt added that the injury, first sustained at a warmup tournament in Sydney, should not affect him in his next match, when he will face the winner of an all Argentinian match between No. 6 Guillermo Coria and No. 9 David Nalbandian.

After three consecutive lefties, Andy Roddick struggled with the serve of right-handed German Philipp Kohlschreiber. But the second-seeded American smacked 15 aces and overcame a second-set letdown to reach the quarterfinals with a 6-3, 7-6 (8), 6-1 win.

"I think I actually had a little trouble getting used to a serve coming from a righty, as weird as that sounds," he said. "Took me a little while to get on it."

He'll face another right-hander next, 25th-seeded Nikolay Davydenko, who beat No. 12 Guillermo Canas 6-3, 6-4, 6-3. Earlier in the tournament, Davydenko eliminated No. 7 Tim Henman.

Roddick allowed the 102nd-ranked Kohlschreiber only one break opportunity while he figured out his righty serve. He was erratic in the second set, doubling his number of unforced errors to 12 and throwing his racket to the court after sending a forehand long.

"I don't think I hit the ball as clean as I did in the first three matches," he said. "I just felt like I was fighting it a little bit more. I'm not too concerned. The good thing is I don't feel like I had my best day, and we're here talking about a three-set win."

Along with Venus Williams, Anastasia Myskina, the French Open champion, and No. 6 Elena Dementieva, the runner-up at the French and U.S. Opens, were eliminated.

Myskina and Dementieva were among seven Russians to make it to the round of 16, but only Wimbledon champion Maria Sharapova and U.S. Open titlist Svetlana Kuznetsova reached the quarterfinals. They will face each other on Tuesday, when men's No. 1 seed Roger Federer will try to keep his 25-match winning streak alive against four-time Australian Open winner Andre Agassi, seeded eighth.

Myskina had 45 unforced errors in her 6-4, 6-2 loss to 19th-seeded Nathalie Dechy.

"I couldn't focus during the match, I lost a lot of easy balls," Myskina said. "I think I have to forget this match."

Dementieva led 12th-seeded Patty Schnyder by a set and two breaks before losing 6-7 (6), 7-6 (4), 6-2.