Updated

Following two days of rain-outs, round victories.

Rain wiped out all of the scheduled action here on Tuesday, and only about 15 minutes of tennis was staged on Wednesday because of inclement weather at the USTA Billie Jean King National Tennis Center.

On Thursday, a second-seeded Nadal handled fellow left-hander Gilles Muller of Luxembourg 7-6 (7-1), 6-1, 6-2 at Arthur Ashe Stadium. The match was postponed on Tuesday and halted because of rain on Wednesday, with Muller leading 3-0 in the opening set.

Nadal moved on in 2 hours, 8 minutes, as Muller piled up 43 unforced errors and had his big serve broken six times by the fiery Spaniard.

The capable Muller stunned Nadal in a second-round affair at Wimbledon back in 2005, but Nadal avenged that defeat by besting Muller in the third round at Wimbledon 2011 earlier this summer.

The 10-time major champion Nadal is the reigning U.S. and French Open titlist. He beat Serbian star Novak Djokovic in last year's finale in Flushing.

Up next for Nadal will be his fellow former world No. 1 Roddick.

"He's having one of the best careers, being in the top players for, I don't know, 11 years, 10 years, 9 years. That's a lot. That's amazing," Nadal said of Roddick. "So I have big respect for Andy, especially he's very tough to be there for a long time and he did."

A 21st-seeded Roddick held off fifth-seeded gritty Spaniard 6-3, 6-4, 3-6, 6-3 on the 584-seat Court 13.

Roddick-Ferrer commenced at Armstrong Stadium on Wednesday before rain halted play after about 15 minutes.

On Thursday, Roddick and Ferrer played two games before the American star complained that water was seeping up through a crack just beyond one of the baselines on the court at Armstrong. Following a lengthy delay in an attempt to fix the problem, the players were moved to an open court, which turned out to be the intimate Court 13.

Following the bizarre court change, Roddick would prevail in 2 hours, 39 minutes by swatting 19 aces and breaking Ferrer on four occasions. The Spaniard settled for 12 aces and two breaks in a losing effort.

"It's difficult for us, because, you know, two days raining; today it was not raining, but the court is not at good performance," a frustrated Ferrer said. "So it was not easy. But, you know, I can't do anything like this."

The USTA released a statement regarding the Armstrong court.

"We have faced an inordinate amount of rain in August and through the early part of September which has saturated the court surfaces at the USTA Billie Jean King National Tennis Center. All courts were completely dried prior to play on Thursday, September 8. However, as the sun began to warm, or "bake" the courts, evaporation of these saturated conditions began to surface on Louis Armstrong Stadium. Until this situation is rectified, no further play will occur on Louis Armstrong Stadium."

The 29-year-old Roddick captured his lone major title here in Flushing back in 2003 and was the runner-up here in 2006. He's 2-0 in his U.S. Open semifinal appearances.

Roddick will now meet Nadal for a 10th time, with the Spaniard leading the all-time series 6-3. The American topped Nadal in the second round at the 2004 U.S. Open.

Fourth-seeded 2008 U.S. Open runner-up Andy Murray flattened 22-year-old American Donald Young 6-2, 6-3, 6-3 on the Grandstand court. The match was suspended on Wednesday, with Young leading 2-1 in the first set. But the American was no match for the talented Brit on Day 11.

Murray, who closed out his Thursday exercise with a resounding ace, ultimately dismissed the overmatched Young in just under two hours, as the American littered the court with 53 unforced errors and had his serve broken a whopping eight times.

Young stunned Murray in the second round at an ATP Masters event at Indian Wells earlier this season.

The three-time Grand Slam runner-up Murray was this year's Aussie Open runner- up to Djokovic and lost to the great Roger Federer in the 2008 U.S. Open finale.

Up next for Murray will be 6-foot-9 John Isner.

Roddick wasn't the only American to reach the quarters on Day 11, as a 28th- seeded Isner upended 12th-seeded Frenchman Gilles Simon 7-6 (7-2), 3-6, 7-6 (7-2), 7-6 (7-4) on Court 17. The towering Isner will now appear in his first career Grand Slam quarterfinal.

Isner advanced in 3 hours, 39 minutes by crushing 26 aces, which accounted for all of his winners on Day 11.