World number one Rafael Nadal advanced to his first US Open semi-final by battling back to defeat 35th-ranked American Mardy Fish 3-6, 6-1, 6-4, 6-2 early on Thursday morning.
The reigning Wimbledon, French Open and Olympic champion from Spain ousted Fish after two hours and 40 minutes, finishing at 2:10 in the morning and thanking the hearty fans who stayed to the end of a day full of long matches.
"For sure not the best conditions to play any match," Nadal said. "Sometimes schedules are tough. Nothing to do, just accept, go on court and try my best."
Left-hander Nadal was also pleased to have reached the final four in all four Slam events this year thanks to his Flushing Meadows breakthrough.
"For me it was a very important win," Nadal said. "It's a very important thing for me to play all the semi-finals in the Grand Slams in the same year.
"I'm very happy for being the first time in the semi-finals of the US Open. For sure you want to play good in all places. In the past here I did not always do well."
In Saturday's semi-finals, Nadal will face British sixth seed Andy Murray, who reached his first Grand Slam final with a 7-6 (7/2), 7-6 (7/1), 4-6, 7-5 victory over Argentina's 19-year-old Juan Martin Del Potro.
"It's going to be very difficult. I'm going to have to play my best," Nadal said. "He's coming with big confidence. He's doing very well. I expect a very tough match."
Saturday's other semi-final pairing will be decided later Thursday when four-time defending champion Federer meets Luxembourg qualifier Gilles Muller and Serbian third seed Novak Djokovic faces US eighth seed Andy Roddick.
Nadal could match Rod Laver, Pete Sampras and Roger Federer as the only men to win three Slam titles in a row in the 40-year Open era. The only Spaniard to win the US Open was Manuel Orantes in 1975, when the event was played on clay.
Nadal, 22, has won an ATP-best 41 hardcourt matches this year and seeks his ninth title of the season. He has won 54 of his past 56 matches, losing only to Juan Carlos Ferrero at Rome and Novak Djokovic at Cincinnati.
"When you are in semi-finals, it's a very good tournament," Nadal said. "I have to be happy to be in the semi-finals. Otherwise I would be pretty stupid, no? The season is long and I'm a little tired but I'm still doing pretty well."
Nadal improved to 5-0 against Fish, who had not taken a set off the Spaniard until the clock struck midnight at Arthur Ashe Stadium.
Hard-serving Fish took advantage of his only break-point chance of the first set and denied Nadal on three break opportunities to claim the first set in 39 minutes, firing 23 winners and winning 16 of 18 first-serve points.
"Mardy played very well in the first set, served unbelievably well," Nadal said. "He played well from the baseline. I always try to start strong but he started stronger than me."
Nadal broke Fish twice in the second set and again in the third without response from Fish. Nadal broke Fish at love in the third game of the fourth set, after which Fish spat on his racquet and smashed it on the ground during a changeover break. Nadal broke again to 5-2 and held to finish the triumph.
Fish, who had never been past the second round of the US Open in eight prior appearances, was denied his first Grand Slam semi-final.
Murray broke the 17th-seeded South American's 23-match win streak, ensuring the lanky 21-year-old Scotsman would jump to a career-high fourth in the world rankings, matching the top mark by any man in British history.
"There were some intense moments but I was just glad to come through," said Murray. "He was on an unbelievable winning streak. He had confidence. I knew I was going to have to fight a lot."
Murray pushed Nadal to five sets in their first meeting, in the fourth round of last year's Australian Open, but has not taken a set off him since.
Murray won titles this year at Doha, Marseille and Cincinnati to give him six career ATP crowns.
The Scotsman has won 17 of his past 19 ATP matches, losing only to Nadal in the quarter-finals at Wimbledon and the semi-finals at Montreal in the run, which continued despite a tough fight from teen titan Del Potro.
Serving to force a fourth-set tie-breaker, Del Potro netted a forehand to give Murray two match points. Del Potro saved the first with a service winner but sent a backhand wide to end the drama after three hours, 58 minutes.
"I'm very relieved. I had my chances to put it away earlier and let it slip away," Murray said. "It feels great to be in the semi-finals. After a match like that it makes it feel even better."