NEW YORK -- World No. 1 Novak Djokovic wasn't outplaying his longtime rival Andy Murray early in Thursday's quarterfinal match as much as he was escaping him. In the first eight games, Djokovic lost one break point, then another, and another -- only to break back and blitz Murray in the first tiebreaker to steal the opening set. The Serbian star survived another stretch in the middle of the match when he couldn't trust his own forehand. Then came another long run of games in which Murray was cracking off so many booming winners with his own forehand that Murray actually allowed himself a rare on-court smile at one point.
But by the end, Djokovic did the same thing to Murray -- his friend and rival since childhood -- that he has done while beating him six of the past seven times they've played. He again succeeded in pushing eighth-seeded Murray so far to the point of distraction and fatigue -- this time, taking the match by the final score of 7-6 (1), 6-7 (1), 6-2, 6-4 -- that Murray spent one entire changeover angrily talking out loud to himself in his chair. He cussed. He gestured angrily. He called himself "terrible." Or worse.
Near the end of the third set, he started staggering around the baseline, as if in pain.
In the fourth, with his hips and back stiffening, he called for a trainer.
By the end, it wasn't quite the epic or instant classic Djokovic's coach, Boris Becker, predicted it might be beforehand.
"Sometimes," Djokovic admitted afterward, "the tennis was not so nice."
But it was another exhaustive study in why Murray-Djokovic is the best rivalry in men's tennis when Rafael Nadal goes missing like he is now. And sometimes even when Nadal is still around.
Murray and Djokovic whaled at each other for 3 hours, 32 minutes, all told.
Their match didn't end on Arthur Ashe Stadium until 1:15 a.m. ET.
When asked in his on-court interview for his thoughts about advancing into a semifinal matchup against Japan's Kei Nishikori on Friday, Djokovic broke into a weary smile and said, "My thoughts are just directed to sleeping right now -- or party. What do you say? Let's party!" Djokovic joked to the smattering of fans remaining.
Murray and Djokovic always mention how they're very similar in style -- same great court coverage, same variety of shots, same determination to win. They are also good friends who practiced for two hours together a few days before the start of the tournament. They have played more than 20 times as pros, and the pattern is always the same.
"When you play against him, you have to be on it physically and mentally, if you want to beat him," Murray said. "Every time we play it's extremely physical."
Djokovic shared similar sentiments.
"I knew coming into this match, it would be tough," Djokovic said. "He'd be going for all his shots. And the aggressive one would win it. I was happy to stay fit."
Another thing Murray and Djokovic share is that neither has had the best of summers by his standards.
Murray, 27, hadn't beaten a top-10 player -- let alone won a title of any kind -- since his watershed career moment in July 2013 when he became the first Brit since 1936 to win Wimbledon. Then, this March, Ivan Lendl quit as his coach, a decision that Murray said "gutted" him. By June, Murray surprised many folks by hiring Amelie Mauresmo, the former French star and two-time Slam winner, after he fell out of the French Open in the semifinals.
So far, their four-tournament partnership has resulted in a lot of talk about how happy they are to be working together and some niggling improvement, but still not the kind of results Murray wants, although he's nearly a year removed from back surgery.
And Djokovic? The Serbian star has his own challenges, odd as it sounds when a championship here -- coupled with his Wimbledon victory and march to the French Open final -- would make him the tour's clear-cut player of the year.
Djokovic, 27, was married shortly after winning Wimbledon, and he and his wife have their first child due in a little over two months. He arrived in New York talking about how his priorities have shifted. He said that "tennis is definitely not No.1 anymore" and "It's family life. Love is more important than work, in my eyes."
But does he mean it literally? It seems so only to a point.
When asked how his change in emphasis or the emotionally draining past two months might change his expectations of winning this tournament, Djokovic shot back, "No, it doesn't. I have high expectations for myself. I always have. Especially at this stage of my career where I feel now is the time I'm at my peak physical strength."
Murray, too, cited Djokovic's fitness as the difference Thursday night.
And Djokovic should again be the fresher player by far when he meets Nishikori, who has played back-to-back five-setters, including a four-hour marathon win over Stan Wawrinka. Nishikori is enjoying a little career renaissance since hiring former American star Michael Chang as his coach. He's a terrific mover around the court himself.
But Murray came into Wednesday's match having spent 3½ more hours on court than Djokovic did. And Djokovic has said that's part of his grand plan, too. He has pointed out he could keep trying to outlast and outrun everyone, same as he used to on his way up to No. 1 and his seven Slam titles, same as he did against Murray on Wednesday night.
"But why spend so much energy if I can actually execute my shots in first two, three shots of the point better?" Djokovic explained. "I want to be more aggressive the first shot after serve and after return. I want to try to get into the court and dominate the rally, dominate the play. That's the goal, you know. It's something I have been working on."
Playing Djokovic is always hard work.
Thursday, he finally served notice for the first time since Wimbledon that his best is on its way back.