Andy Murray's hopes of reaching the US Open final came to an end as Rafael Nadal outclassed him in four sets to set up a meeting with Novak Djokovic.
The British number one lost 6-4 6-2 3-6 6-3 in three hours and 24 minutes to ensure his wait for a maiden Grand Slam title goes on.
Murray was no match for the Spaniard in the first two sets and despite rallying in the third, he wilted in the fourth.
Nadal faces Djokovic on Monday after .
"Tonight I played my best match so far and I'm very happy to be in the final," said the world number two.
"The beginning of the fourth set was really important because Andy had a break point but I managed to save it."
Murray beat Nadal at this stage in 2008 to reach his maiden Grand Slam final, but Nadal had won each of their previous four meetings and it was swiftly clear why.
The second seed had a clear game plan and stuck to it, played with maximum aggression from the first point, targeted Murray's weaknesses and stayed calm at all times.
By contrast, Murray struggled to execute his strategy, lacked intensity, was unable to take Nadal out of his comfort zone and wasted energy berating himself.
The Scot dug deep to save a break point and hold firm in an eight-minute opening service game, and registered a chance of his own in game six.
But he failed to capitalise as Nadal came up with one of numerous stunning forehand winners - and he was soon in total control.
Nadal broke in game seven when Murray framed a return and easily saw out the opening set.
He came under severe pressure in game two of the second but again Murray could not capitalise, squandering three break points.
Nadal was left to applaud an incredible Murray forehand in game three but there were no niceties when the 10-time Grand Slam champion forced an error to break for 3-2.
Murray looked to be feeling the effects of and Nadal struck again to move 5-2 ahead before securing a two-set lead with an imperious hold to love.
The momentum swung both ways in a high-quality third set and it was Murray who made the first move with a volleyed put-away in game two.
A first double-fault of the match helped Nadal hit straight back, but Murray stuck with him brilliantly, regained his composure and cut down on the errors.
He was rewarded with a hard-earned break of serve for 5-3 and then converted his third set point when Nadal netted a forehand.
Murray's big chance came at 1-1 in the fourth but, after reeling Nadal in from 40-0, he netted a backhand on break point.
Punishment was instant as Nadal broke for 3-1 and then again to seal victory when the world number four put a backhand into the tramlines.
It is the third time this season that Murray has lost to Nadal in a Grand Slam semi-final.
"I've got to improve," he said. "It's disappointing to get so close. I've lost to Rafa a few times this year. I need to work on my game and get physically stronger.
"I was disappointed with the first two sets but the third and fourth were better. I know the right tactics for playing against Rafa but I didn't implement them in the first two sets.
"It's very easy from the side to suggest what I should be doing out there - you should see some of his passing shots. There's many things I could have done a bit better but I didn't.
"He's probably the greatest player who has played tennis."
Austria's Jurgen Melzer and Germany's Philipp Petzschner won their second Grand Slam doubles title, beating Poland's Mariusz Fyrstenberg and Marcin Matkowski 6-2 6-2 in the men's doubles final.
The unseeded teenage American pair Melanie Oudin and Jack Sock won the mixed doubles title, beating eighth seeds Gisela Dulko and Eduardo Schwank of Argentina 7-6 4-6 10-8.