NEW YORK - The Williams sisters have played these formless slugfests before, but this one, the 14th in a series that long ago lost its novelty, was particularly flat.
If there was one surprise yesterday, it was that Serena Williams, still several miles from working herself back to championship fitness, had a set point in this 7-6 (5), 6-2 loss to her older sister.
Everything else was as predictable as a metronome. Big hits followed by big misses followed by power grunts followed by Serena's shrieks of frustration.
After 1 hour, 28 minutes, in a match that had all the electricity of a Parcheesi final, Venus was through to the quarterfinals with her 11th consecutive Grand Slam victory, which includes, of course, her tour de force at Wimbledon. She also has now won 22 of her past 23 Grand Slam sets.
The win evens the series between them at seven apiece and gives Venus two straight wins after having lost six in a row. She also beat Serena in Key Biscayne, Fla.
Venus was joined in the final eight by top-seeded Maria Sharapova, who raced past India's Sania Mirza, 6-2, 6-1; by No. 4 Kim Clijsters, a 6-1, 6-0 winner over Maria Vento-Kabchi; and by No. 9 Nadia Petrova, who eliminated 16-year-old future star Nicole Vaidisova, 7-6 (4), 7-5.
The sisters knew this was no classic.
"We were talking in the locker room about just how horrible we played," Serena said. "I said, 'You were terrible.' She was like, 'I know.' It was definitely a match we could have played better."
They combined for 36 winners and 59 unforced errors, which is not a good ratio, and Venus at 19 and 29 was nothing special even in victory. After cracking forehand killers in the first three rounds, it seemed as if she couldn't hit three forehands in a row.
But when the dust cleared, the only thing that mattered was that Venus, seeded 10th, was in the quarters to play Clijsters, who is favored by many to win her first Grand Slam title.
"I've had more opportunity to practice and train than [Serena] has, so I think that gave me the edge," said Venus.
Serena came into the Open having played only five matches since April because she was recovering first from a knee injury, then an ankle sprain.
If she's carrying more weight than normal, it wasn't visible. But there was no question about her fitness. She tired badly in the second set and did a lot of stumbling around the court trying to retrieve her sister's zingers to the corners.
Sharapova next faces Petrova in a battle of Russians and this is the round where Petrova went down, with some nervousness, last year to eventual champion Svetlana Kuznetsova.
"I was really ready for the Open," Sharapova said. "It was a bit unexpected because I didn't play a lot of matches coming into the tournament, so I thought I would be a little rusty at the beginning.
"I surprised myself in the first round, that's for sure. Played a rough opponent [Eleni Daniilidou of Greece]. That gave me more confidence."
Serena got her lone set point in the 12th game of the opening set, but Venus fought it off with a body-shot service winner. They then went into a tiebreaker, which reached 5-5 before Venus tapped a backhand volley into the open court and Serena slammed a backhand into the net.
Serena had six aces, but six double faults. Venus had one ace and four doubles. She had 13 break-point opportunities, but converted only three. On this afternoon, however, that's all she needed.
In men's matches yesterday, defending men's champion and top seed Roger Federer advanced to the round of 16 with a 6-3, 7-6 (6), 6-2 victory over Olivier Rochus. Federer next plays Nicolas Kiefer.
Former U.S. Open champion Lleyton Hewitt barely escaped the same fate as French Open champion Rafael Nadal.
A day after James Blake knocked the No. 2 Nadal out in the third round, American Davis Cup teammate Taylor Dent came close to ousting the third-seeded Hewitt in a five-set thriller in the same round at the U.S. Open.
Dent, best known for his role as the hitting partner of the actor who played the son of Andre Agassi and Steffi Graf in a TV commercial, wasn't acting when he produced some of the best tennis of his career before going down to Hewitt, 6-3, 3-6, 6-7 (2), 6-2, 7-5.
Hewitt next plays No. 15 Dominik Hrbaty, who beat No. 17 David Ferrer, 6-7 (7), 7-5, 7-5, 7-5.
Italy's Davide Sanguinetti won the longest and perhaps most exciting match of the tournament so far, beating Thailand's Paradorn Srichaphan, 6-3, 4-6, 6-7 (2), 7-6 (6), 7-6 (5), in 4 hours, 24 minutes.
Finland's Jarkko Nieminen grabbed a spot in the fourth round by knocking off No. 30-seeded Max Mirnyi, 6-3, 7-6 (5), 3-6, 6-3.
"I'm very satisfied with how I've played here," Nieminen said. "There are only 16 players left. It's a great feeling."
Nieminen's next opponent will be Fernando Verdasco of Spain, a 6-1, 4-6, 6-7 (2), 6-4, 6-4 winner yesterday over Novak Djokovic of Serbia.
"He's a very talented player," Nieminen said of Verdasco. "He has the potential to be a really good player. I have to play well to beat him."
It will be a battle of the only two left-handers left in the men's singles. And it is the first time a player from Finland has reached the fourth round at a Grand Slam since Nieminen did it at the French Open two years ago.
Only one other Finn, Veli Paloheimo at the 1990 Australian Open, has advanced this deep in a major tournament.
The South Florida Sun-Sentinel is a Tribune Publishing newspaper. The Associated Press contributed to this article.