Defending champion Rafael Nadal took out his US Open frustrations on Gilles Muller of Luxembourg on Thursday to reach the quarter-finals with a 7-6 (7/1), 6-1, 6-2 victory. The second seed had trailed 0-3 overnight after just 15 minutes of play had been possible on Wednesday, but with bright sunshine replacing two days of heavy rain, the Spaniard raced into the last eight. Next up for the champion is either 21st-seeded American Andy Roddick or Spanish compatriot David Ferrer for a place in the semi-finals. Nadal, whose fourth round match had originally been slated for Tuesday, had led a player revolt on Wednesday, angry at having to go on court when the Arthur Ashe Stadium surface was still damp and with rain still in the air. He had claimed players' safety was being compromised by tournament officials desperate to clear the backlog caused by the downpours which left him having to play four days in succession if he was to make Sunday's final. "It was a tough day yesterday for the players and the fans who waited many hours. Sorry about that, but thanks for still being here," said Nadal. "After the last two days, I am happy to be through. I played well against a very tough player. "The situation yesterday was not easy for us and the organisers. They tried their best but they were wrong. Everyone makes mistakes." Nadal has endured a dramatic US Open, collapsing with cramping at a news conference after his third round win over David Nalbandian before his frustrating two days waiting for the rain to clear. He made up for lost time on Thursday, taking less than two hours to complete victory over the 68th-ranked Muller who he had also defeated at Wimbledon this year. Breaks in the second and fourth games of the second set proved enough for a comfortable lead and he was quickly 2-0 up in the third. Muller, the junior champion in New York 10 years ago, retrieved the break for 2-1 but further breaks for Nadal in the fifth and seventh games put the tie beyond his opponent's reach. Victory was secured after 2hrs 08min with a smart backhand volley.