NEW YORK -- At 1:43 p.m., the announcements began over the loudspeakers in the lounges and locker rooms of Arthur Ashe Stadium.

"Attention players," the voice intoned. "Ai Sugiyama and Francesca Schiavone, please report to player operations." A pause. "Anastasia Myskina and Mary Pierce, please report to player operations."

And on it went Thursday, a roll call of tennis pros promptly shuttled out to courts large and small around the National Tennis Center, eager to play after four days of postponements and suspensions. There were two more rain delays -- it wouldn't have seemed right otherwise -- but from 4:45 p.m. on, there was tennis everywhere.

No. 1-ranked Kim Clijsters moved a step closer to her first Grand Slam title, beating No. 5 Amelie Mauresmo 6-1, 6-4 to set up a semifinal against 1998 Open champion Lindsay Davenport, who defeated No. 24 Paola Suarez 6-4, 6-0.

Three-time major champion Jennifer Capriati also reached the semifinals, which will be played tonight, by eliminating No. 29 Schiavone 6-1, 6-3.

Meanwhile, Andre Agassi and Andy Roddick finally have six fellow quarterfinalists after 2001 champion Lleyton Hewitt, No. 3 Juan Carlos Ferrero, No. 5 Guillermo Coria, No. 12 Sjeng Schalken, No. 13 David Nalbandian and No. 22 Younes El Aynaoui won Thursday.

Nalbandian registered the biggest upset on paper, knocking off No. 2 Roger Federer, the reigning Wimbledon champion, 3-6, 7-6 (1), 6-4, 6-3. Nalbandian has won all five of their pro meetings.

Clijsters took a 3-2 head-to-head edge into her match against Mauresmo, who made 34 unforced errors -- 21 more than the Belgian.

"I just tried to rest as good as possible and try not to worry about the weather, because it was pretty frustrating," said Clijsters, who led 3-0 when the match was stopped because of rain Wednesday. "The first few days it happened, the players were laughing. The more we saw the rain coming, we just got more depressed -- all of us."

If the tournament stays on schedule, the men who played Thursday would have to play four matches in four days, while Agassi (who won his fourth-round match Tuesday) and Roddick (Wednesday) will be fresher. Agassi plays Coria on Friday, when Roddick faces Schalken.

"It was very, very tough for everybody," Nalbandian said. "Agassi and Roddick get an advantage over everybody else. But I think I'm ready to play four matches in a row."

Because a total of only four matches were completed from Monday through Wednesday, the tournament began Thursday with a backlog of 174 matches. That was alleviated somewhat by the cancellation of the junior doubles events, while junior singles matches were moved to an indoor tennis club 25 miles away.

How good was the weather in the afternoon and evening? There even was time for the twice-postponed Michael Chang retirement ceremony on center court, and the first doubles results since Sunday, including Navratilova and Svetlana Kuznetsova beating Henrieta Nagyova and Maja Matevzic 6-2, 6-3.

Still, there were ways in which the U.S. Open went from the submerged to the ridiculous Thursday.

Organizers scrambling to squeeze in matches were deprived of a show court because the Grandstand had absorbed too much water and couldn't be dried enough for play. And Schiavone's 6-7 (5), 7-5, 6-2 fourth-round win over No. 15 Sugiyama was interrupted when the chair umpire was hit and hurt by a ballboy's throw.

Schiavone-Sugiyama goes into the books with an official elapsed time of 2 hours, 36 minutes -- but the match ended 66 1/2 hours after it began.

It started Monday night and was suspended at 6-6 in the first set, then resumed Tuesday, and Sugiyama served for the match at 5-3 in the second. She lost that game, and the match was halted. They were washed out entirely Wednesday, then were called out to play a little before 3 p.m. Thursday, four hours after they were scheduled to start.

Schiavone won three straight games to take the second set, but fell behind 2-0 in the third. That's when play was stopped by the errant ball toss.

"I saw it coming out of the corner of my eye just before it hit me," said chair umpire Lynn Welch, who oversaw the 2002 Open women's final. "I was thinking: 'That's ironic. We just get back out here, and now there'll be a delay because I'm hit."'

Welch was given a plastic bag filled with ice to put on cuts to her nose and temple, and she soldiered on.

Three minutes later, play was stopped because of rain.

When they came back out, Welch was wearing a Band-Aid, and Schiavone won six straight games to end the match. When Sugiyama floated a backhand wide on the final point, Schiavone raised her arms, dropped to her knees and covered her face, trembling.

All told, there were seven stops-and-starts in the match, and that doesn't count when Schiavone held up play to swat a bothersome bug and sweep it away with her racket.

"A crazy match," Sugiyama said. "I understand with this weather it's tough for everyone. But it is hard to keep a good balance. Having a match over four days: It happened here. I don't think it's going to happen again."

There were other touches of the bizarre.

Federer and Nalbandian came out of a rain delay to play one point before being sent to the locker room. Nalbandian plays El Aynaoui, who eliminated No. 7 Carlos Moya 7-6 (4), 7-6 (7), 4-6, 5-4.

Hewitt's match, a 4-6, 6-2, 6-4, 6-2 victory over No. 11 Paradorn Srichaphan, was switched from the Grandstand, where the water level underneath is so high that the surface feels soggy even when the water on top has been wiped away.

They were sent to Court 11, where a scoreboard wasn't working. Hewitt next plays No. 3 Ferrero, who will make his debut in the U.S. Open quarterfinals after getting past Todd Martin 6-2, 6-4, 3-6, 5-7, 6-3.

"It's not easy to sit around for a number of days," Martin said. "But it's all of our jobs, that when the time comes, we're ready to take care of business."