NEW YORK -- Contorting his body while sliding into shots, Novak Djokovic used his typical relentless defense to reach the U.S. Open semifinals for the seventh year in a row.

Not quite as unflinchingly dominant as he was during his first four matches in the tournament, the top-seeded Djokovic quickly overcame a one-set lull Thursday night against 21st-seeded Mikhail Youzhny of Russia before finishing off a 6-3, 6-2, 3-6, 6-0 victory.

"Level of confidence is right at the top, very close, because I have been playing most of my matches here very aggressive, very dominantly," Djokovic said. "I have been very satisfied with my performances overall in the whole tournament so far. And even tonight, even though I dropped a set, I feel I was in control."

It put Djokovic in his 14th consecutive Grand Slam semifinal, a 3½-year stretch that is the second-longest in men's tennis history. Roger Federer's record is 23.

"I've been always trying to play my best tennis at Grand Slams," said Djokovic, whose six trophies from his sport's most important tournaments include the 2011 U.S. Open.

He won the first 14 sets he played these two weeks, taking under two hours to advance each time. But he faltered against Youzhny in the third, making 16 unforced errors and getting broken twice -- the only service games Djokovic lost in the match.

"After I lost (the) third set, I definitely tried to regroup and focus on every point individually and start playing the same game that I had in first two sets," Djokovic said.

He will face ninth-seeded Stanislas Wawrinka, who upset defending champion Andy Murray 6-4, 6-3, 6-2 on Thursday to reach his first major semifinal.

While Youzhny made things interesting for a short while, Djokovic made sure there would not be another big surprise.

Now he gets a chance to try to reach a fifth U.S. Open final. In addition to his title, he was the runner-up in New York in 2007, 2010 and 2012.

That loss a year ago came against Murray, who also beat Djokovic in the Wimbledon final this July.

But Djokovic doesn't need to worry about that happening again.

Instead, the six-time major champion will face Wawrinka. Djokovic has won 12 of their 14 tour matches, including the last 11. The most recent came on the hard courts of January's Australian Open, when Djokovic edged Wawrinka 12-10 in a fifth set en route to the championship.

"Definitely one of the most exciting matches I have played in my life on this surface," Djokovic said.

Youzhny is one of the dozen active men who have reached the quarterfinals at each of the four Grand Slam tournaments at least once, and he made it as far as the semifinals at New York twice, in 2006 and 2010. But what he might be best known for are some of his on-court antics, including once bashing himself in the head with his racket hard enough to draw blood.

Coming off a draining five-set victory over 2001 U.S. Open champion Lleyton Hewitt in the fourth round, Youzhny started slowly Thursday.

He finally converted his eighth break chance, 100 minutes into the match, in a game that included a lunging retrieval of a drop volley. That gave him a 3-1 lead in the third set, and when he held serve to go up 4-1, Youzhny let out a guttural yell.

After Djokovic broke back to get within 4-3, he went through another letdown, and double-faulted to lose serve yet again. Youzhny steadied himself and served out the set.

But Djokovic did not permit the rest of his big lead to slip away, breaking in the second game of the fourth set to regain control at 2-0.

"He was much better and much (fresher) in the fourth set," Youzhny said.

In what would turn out to be the last game, with Djokovic two points from victory, Youzhny hit a running backhand down the line for a winner and basked in the moment, raising his arms and enjoying the roar of the crowd. The shot was so nice that even Djokovic applauded.

But really, this was Djokovic's night.

He saved the first seven break points he faced, including one while trying to serve out the opening set. Then, on his third set point, a 14-stroke exchange, Djokovic flicked a desperation lob that Youzhny hammered with an overhead smash. Somehow, some way, Djokovic sprinted over for a stretching flick of a backhand that Youzhny netted.

Djokovic wheeled toward his guest box -- British business magnate Richard Branson was among the supporters there -- and flexed and pumped his arms while screaming.

It's the sort of thing that happened over and over and over: Youzhny would appear to have won a point, and Djokovic would make it last a little longer.

"Every point, you have to play. He never (misses)," Youzhny said. "He never (gives) you some presents. OK, maybe one, two, but not (consistently)."