By Larry Fine
In the end, the Scotsman's body betrayed him and he was eliminated 7-6 (1) 6-7 (1) 6-2 6-4 in a three hour 32 minute quarter-final that gave him some optimism going forward.
Murray has yet to win a title since last year's Wimbledon and his subsequent back surgery, but on Arthur Ashe Stadium there were glimpses of his full power.
"I played well," he told reporters as the clock neared 2 AM on Thursday morning. "Especially the first couple of sets was some good tennis.
"I was down in the first set and I fought back. I was down in the second set and a break and I fought back. So I fought hard. I played some good tennis. But it wasn't enough.
"Right now I'm obviously disappointed. It's extremely late. I'm tired. I don't feel particularly proud right now. I feel disappointed. But I think there was some good tennis.
"Hopefully I can build on that."
After giving as good as he got over the first two sets, Murray began to wear down late in the third. He walked gingerly, leaned on his racket like a cane, and picked his spots to cut loose on his groundstrokes.
"I got stiff in my hips and my back towards the end of the third set," said Murray. "I didn't hurt anything. It was just I think fatigue and I stiffened up."
Murray said playing against his old friend and rival Djokovic was a good measuring stick.
"Maybe, I haven't played enough matches at that level this year," the eighth seed said. "I mean, it's obviously different playing against the number one in the world, and the way that we play against each other, it's just an extremely physical match.
Murray said locking horns with Djokovic was the ultimate test, one he passed in 2012 when he beat the Serb in five sets to win the U.S. Open crown for his first grand slam title.
And passed again in three long sets when he claimed his treasured Wimbledon triumph.
"Whereas, maybe when I play against Roger (Federer), for example, it's quicker points. So physically, that's not as demanding.
"But when me and Novak play against each other - you obviously see very tight, long rallies. Both of us do a lot of running. Maybe I'll gain a lot from playing a match like today.
"Because it doesn't matter how much training you do, when you get on the match court it's different. I can't practice with the best player in the world, so it's tough to practice at that intensity."
Before the stiffness set in, Murray was ripping forehands with sizzling gusto and seizing the moment to unleash winners.
It was enough to make him wish there were more grand slams remaining on the 2014 calendar.
"I played some nice tennis at times," he repeated. "It's a shame. Obviously, the slams are over for this year, so I have to wait a few months before the next one."
(Reporting by Larry Fine; Editing by Patrick Johnston)