Third seed Novak Djokovic saw off Spanish veteran Carlos Moya 6-4 7-6 (9-7) 6-1 to book a US Open semi-final against David Ferrer.
The 20-year-old found his form when it mattered, edging a tight first set by breaking serve at 5-4.
The Serb then survived a set point in the second-set tiebreak before winning it with a brutal forehand.
A downcast Moya was broken in the first game of the third set and Djokovic hit cruise control to wrap up the match.
"It's always good to win in straight sets," said Djokovic, who was just 11 when 31-year-old Moya won his only Grand Slam title at the French Open in 1998.
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"I knew that Carlos is a very good player, a competitor, a former number one. He has a lot of experience on the big matches on the big courts.
"He had a great tournament but luckily I played my best tennis and had more luck in the second-set tiebreak. In the third set, I played really well."
Djokovic, who has now won 54 of the 73 tiebreaks he has played, added: "I cannot say that I'm stronger mentally when I get to the tiebreak.
"But it's certainly an advantage when you see you have such a great record."
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