Australian Open champion Djokovic and French Open winner Nadal have designs on adding a second Grand Slam to their honours this year but first must get past familiar foes in Swiss Stanislas Wawrinka and France's Richard Gasquet, respectively.
Top-seeded Djokovic, who advanced to his 14th successive Grand Slam semi-final with a four-set victory over Mikhail Youzhny, and Nadal, a straight-sets winner over fellow-Spaniard Tommy Robredo, have both lost only one set in the tournament.
The darkhorse challengers, however, are at the top of their games, both wielding lethal one-handed backhands as a key part of their arsenal.
Nadal said there was no danger of him looking past longtime friend Gasquet and at a possible marquee clash with Djokovic.
"I hope to be ready to play a good match against Richard. If not, I will not have the chance to play the final," the second-seeded Spaniard said.
"If I don't play great match against Richard, I will see the final on TV. I am focused only to play great match in semi-finals against Richard."
The eighth-seeded Gasquet went five sets to beat big-serving Milos Raonic of Canada in the fourth round, and went the distance again to eliminate fourth-seeded Spaniard David Ferrer in the quarters.
Wawrinka caused an even bigger splash as he improved his 2013 record to 41-15 by ousting Wimbledon winner and defending US Open champion Andy Murray of Britain in three breezy sets in his quarter-finals tilt.
The Swiss said he was most proud of how he dealt with the pressure of playing against Murray, since in the past he has often been plagued by nerves.
"My level of tennis right now is quite good. I'm really confident with myself, with my game," said 28-year-old Wawrinka, whose victory over third seed Murray lifted him to his first Grand Slam semi-final.
Djokovic knows first-hand how dangerous Wawrinka can be, having gone through a titanic five-set struggle against him in the fourth round at the Australian Open that he clinched 12-10 in the final set of a superb contest.
"It's definitely one of the most exciting matches I have played in my life on this surface, that was played on a very, very high level," the Serb said about that hard court encounter in Melbourne on his way to winning a third straight Australian crown.
"In the past we all knew that he has the quality to play that well, but not in a consistent basis.
"He's a very complete player. He can play equally well on any surface. He had one of the best seasons in his life."
Wawrinka said the contest against Djokovic was a turning point for him.
"It's one of the keys of the season, for sure," the Swiss said. "That was a really tough moment, but at the end, I was really positive with that match because all Australian Open my level was quite good and was better than ever."
Djokovic said he was bracing for Wawrinka's best after his impressive performance against Murray.
"That was quite impressive," he said. "I'm sure he's very confident and he has nothing to lose now. He's going to go for the win."
Djokovic leads their head-to-head series 12-2, with wins in their last 11 meetings.
Nadal is a perfect 10-0 against Gasquet, who he has competed against since their junior days.
The Spaniard said he had great respect for his opponent and was pleased to see him make it to the last four at Flushing Meadows.
"He's a nice guy, very nice person, one of the players on the tour that I feel closer (to) because we are from the same age. We always had a good feeling," said Nadal.
"So it's great, no? When you see a player like Richard that we grow up in similar ways and we played when we were kids. We have the chance to be in the semi-finals of the US Open, so is great."
Even Djokovic felt good about Gasquet's advance to his second Grand Slam semi-final following his maiden journey six years ago at Wimbledon.
"Richard was always one of the most talented players that played the game with one of the most beautiful and also most efficient backhands that we have seen," said Djokovic.
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- Richard Gasquet
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