NEW YORK (AP) -- Rafael Nadal looked lost, swallowed up by the huge serves and crushing forehands coming at him from his 6-foot-6 opponent across the net.
That was Juan Martin del Potro, who made his first Grand Slam final, handing Nadal a 6-2, 6-2, 6-2 loss Sunday at the U.S. Open -- the worst loss Rafa has suffered in a major tournament.
"I think this is the best moment of my life," del Potro said.
Nadal was dealing with a strained abdominal muscle, and after the match he finally admitted the obvious -- that it was bothering him.
The six-time Grand Slam tournament champion also gave plenty of credit to del Potro, who deserved every bit of it after sapping all the life, and hope, out of a player whose relentlessness is one of his biggest attributes.
"I'm going to repeat: He played much better than me, and for that reason he beat me," Nadal said.
The sixth-seeded Argentine -- the first from that country to make a U.S. Open final since Guillermo Vilas in 1977 -- kept No. 3 Nadal pinned behind the baseline with a deep, flat forehand and a first serve he mixed at between speeds from the 90s to the 130s.
In the first set, Nadal put on his usual show, battling for every point, never giving in, even though it was clear he was being overpowered and playing at less than 100 percent. The first four games crept along, at 27 minutes.
But he couldn't convert any of the five break points he had against del Potro's huge serve over the first 12 games, couldn't do much to neutralize an opponent who hit 33 winners, often running around the ball to pound forehands down the line. And there was no waiting out this storm, no hoping del Potro might weaken, the way he did earlier this year at the French, when he was in his first Grand Slam semifinal, leading Roger Federer 2 sets to 1.
Federer came back in that one and might await again. In the final, pushed to Monday because of rain over the weekend, del Potro will play either the five-time defending champion or Novak Djokovic. Del Potro's record against the two: a combined 0-9.
But, he says, he's been seeing the ball great this week.
"Maybe my green eyes. I don't know," he said. "It's very tough playing against Rafa or Roger. But today I play unbelievable, and that was the key."
The result prevented the eighth Federer-Nadal final in a Grand Slam and first at the U.S. Open, and left Rafa still in need of a win at Flushing Meadows for the career Grand Slam.
"I'm sorry," del Potro told the crowd in his on-court interview. "But tomorrow, I'll fight until the final point for you, for everyone, to show good tennis."
Del Potro's first major final extends a stretch of improving tennis that began last year when he became the first player to win his first four titles in four straight tournaments. He saw his ranking jump from 65 to 13 and likely up to No. 5 after this tournament.
He had two days off since his quarterfinal win over Marin Cilic and could be seen often, walking the halls at Arthur Ashe Stadium, waiting out two days of rain delays that pushed the men's final back for the second straight year.
Nadal, meanwhile, had to finish his postponed quarterfinal Saturday afternoon, and though that was a stress-free dispatching of Fernando Gonzalez that took 34 minutes to complete, there was no doubting who was in better physical condition for this match.
Eliminated from the tournament, Nadal finally documented the problems he's had with his abdominal muscles, dating to a tournament in Montreal in August. The pain took a toll in many ways, most notably on Sunday when Nadal was serving from the deuce court, against the wind.
"I only can serve in the middle, because if I serve it outside, the abdominal kill me, no?" he said.
Nadal, who missed Wimbledon while resting his hurting knees, said he did not consider this latest injury to be major. Still, he will take some time off, including skipping Spain's Davis Cup match this month.
Del Potro, meanwhile, has a date Monday to try to bring the title back to Argentina for the first time since Vilas did it in 1977.
The best win of his career?
"I think so," del Potro said. "It was so focused every moment because Rafa's a great player. He can run for 5, 6 hours. I'm not very strong but I do my best, and I'm in the final."
Copyright 2014 Associated Press. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.