Even in Thursday's perfect weather, Andy Roddick ran into trouble completing a rain-delayed victory at the U.S. Open -- this time, because of water seeping through a crack behind a baseline in the tournament's second-largest stadium.

At least he finally got to finish a 6-3, 6-4, 3-6, 6-3 win over fifth-seeded David Ferrer, which Roddick celebrated by high-fiving spectators at cramped Court 13. Two days of wet weather gave way to sunshine, and defending champion Rafael Nadal and 2008 runner-up Andy Murray managed to work their way into the quarterfinals, too, by wrapping up straight-set victories.

Still, because of rain earlier in the week, the tournament decided Thursday afternoon to revamp its schedule and push the men's final to Monday at 2000 GMT -- 24 hours later than originally planned. The women's final was shifted from Saturday night to Sunday at 4 p.m. It'll be the fourth consecutive year that the U.S. Open ends on Monday.

Before the change was made, one of the men's finalists faced the prospect of playing four best-of-five-set matches in four days, back-to-back-to-back-to-back, something Nadal called "not fair." Now the men will get Sunday off.

The start-and-stop, fourth-round match between 2003 U.S. Open champion Roddick and Ferrer was supposed to begin Tuesday, when showers washed away all play. They got on court Wednesday, but only for about 15 minutes, enough to play four games. And Thursday, they played for less than 10 minutes -- two more games -- before Roddick pointed out a damp spot in Louis Armstrong Stadium that made it dangerous to play.

So eventually, they were ushered from that 10,103-seat arena over to 584-capacity Court 13, while fans ran and pushed their way up the stairs to the bleachers in the new locale. At one point, Roddick said, he saw someone trying to scale a fence to get a peek at the action.

"I thought the atmosphere was great. People packed in," Roddick said, recalling he last played on Court 13 as a junior in 1999. "I'd rather play a smaller court and have it packed, than playing a bigger court and have it a quarter full."

The U.S. Tennis Association later issued a statement saying: "Until this situation is rectified, no further play will occur on Louis Armstrong Stadium."

Elsewhere, No. 2-seeded Nadal beat 68th-ranked Gilles Muller of Luxembourg 7-6 (1), 6-1, 6-2 in Arthur Ashe Stadium; No. 4 Murray eliminated 84th-ranked Donald Young of the United States 6-2, 6-3, 6-3 in the Grandstand; and No. 28 John Isner got past No. 12 Gilles Simon of France 7-6 (2), 3-6, 7-6 (2), 7-6 (4) on Court 17.

Roddick next faces Nadal with a semifinal berth at stake.

"I'm going to have to play pretty aggressively now, similar to what I did today," the 21st-seeded Roddick said. "He's one of the greatest ever, so I'm going to have to have a repeat, at least."

Murray plays Isner, who reached the first Grand Slam quarterfinal of his career.

On the other half of the men's draw, they already were into the quarterfinals, and No. 1 Novak Djokovic improved to 62-2 in 2011, advancing when his opponent, No. 20 Janko Tipsarevic, stopped playing while trailing 7-6 (2), 6-7 (3), 6-0, 3-0. Tipsarevic had his left thigh bandaged by a trainer at 5-0 in the third set.

Djokovic needed his own visit from the trainer for treatment on a bloody left big toe after sliding to get to a drop shot in the fourth set's opening game.

In the semifinals, Djokovic will face 16-time Grand Slam champion Roger Federer or No. 11 Jo-Wilfried Tsonga, who were scheduled to play Thursday night.

"I was saying I hope it rains tonight," Murray said, "because then everyone is in the same boat, really."

In the women's quarterfinals, 13-time major champion Serena Williams overcame some shaky serving early to beat No. 17 Anastasia Pavlyuchenkova of Russia 7-5, 6-1 and improve to 17-0 on hard courts this season.

"I just kept losing serve in the beginning. Very weird," said Williams, whose older sister Venus watched from the stands.

Seeded only 28th after missing nearly a full year because of health problems, Williams hasn't dropped a set so far heading into a semifinal against top-seeded Caroline Wozniacki, a 6-1, 7-6 (5) winner against No. 10 Andrea Petkovic of Germany on Court 13.

On the other half of the women's draw, No. 9 Sam Stosur will play 92nd-ranked Angelique Kerber of Germany in the semifinals. Kerber upset No. 26 Flavia Pennetta 6-4, 4-6, 6-3, while Stosur easily defeated No. 2 Vera Zvonareva 6-3, 6-3. Zvonareva was the runner-up at the U.S. Open and Wimbledon last year.

Nadal was down a break and trailing Muller 3-0 when play was stopped Wednesday because of rain. He, Roddick and Murray then marched to the office of tournament referee Brian Earley to voice their complaints about the safety of the courts and make the case that they never should have been sent out to play in the first place.

Nadal also raised a bigger concern, which he discussed at his postmatch news conference Thursday: Players should have more say about how Grand Slam events are run.

"The problem is we don't have enough power in these kind of tournaments," Nadal said. "That's what have to change very soon."

One specific criticism he leveled at the U.S. Open is that it's the only major tournament where the men are slated to play the semifinals Saturday, and the final Sunday, without a day of rest in between. He called that schedule "something crazy for the players." But the changes made later Thursday by the USTA rendered that complaint moot this year.

Given all the delays, Roddick was eager to get going against Ferrer somewhere -- anywhere, really.

While workers tried to dry the problematic patch at Armstrong -- caused by a buildup of water just under the court surface being pulled up by evaporation -- Roddick and Ferrer headed to the locker room. About an hour later, at 12:30 p.m., they returned to Armstrong with Earley, and the trio went over to inspect the area together.

Roddick pointed out that the spot still was wet and said to Earley, "Can you tell us why you brought us out here? ... How hard is it to not see water? ... What are we doing here?"

As he walked over to the sideline, Roddick shook his head, saying, "I'm baffled right now. Absolutely baffled." Then he shoved his racket in his bag and walked off the court as some fans booed.

Roddick, Ferrer and Earley then spoke in a hallway of Armstrong stadium.

"Put us on 13. 13's open. Let's go play. I don't care where we play," Roddick said.

Within minutes, the decision was made to switch courts, the match eventually resumed a little before 1 p.m.

Not much more than two hours later, Roddick was a winner.

He hadn't played anywhere at Flushing Meadows other than 23,771-capacity Arthur Ashe Stadium since Sept. 3, 2002, when he beat Juan Ignacio Chela at Armstrong in the fourth round. That was a run of 39 consecutive U.S. Open matches at Ashe for Roddick.

On Thursday, he started a new streak at Court 13.