Murray had not beaten a top-10 player since his emotional victory over Djokovic on Centre Court more than a year ago but played a very fine match in the New York heat to defeat ninth seed Jo-Wilfried Tsonga 7-5 7-5 6-4.
It maintained the Scot's impressive record of having reached at least the quarter-finals of every grand slam tournament he has played in for the past four years.
Tsonga had been having a poor season until Toronto when he beat Novak Djokovic, Murray, Grigor Dimitrov and Roger Federer back to back to lift the joint biggest title of his career.
That took him back into the top 10 and set him up perfectly for the year's final grand slam.
It was a long way back now, though, particularly given the heat and humidity the pair were playing in.
The conditions were arguably tougher than when Murray cramped so dramatically against Haase last Monday but so far there was no sign of any physical discomfort.
What was the same, however, was that Murray had a dip at the start of the third set, serving a double fault to go break point down before Tsonga powered away a return.
He had to work very hard to avoid trailing 3-0, saving two break points, and he got his reward in the next game, breaking back to love to make it 2-2.
Murray had talked in the build-up about the need to recover from any dips quickly and he was certainly doing a good job at that.
There was a far bit of ranting and raving - and some choice language - but Murray kept his focus well and played the shot of the match in the sixth game, slamming a running forehand cross-court winner off a decent Tsonga smash.
The pressure was all on the Frenchman serving to stay in the match at 4-5 and successive double faults was a dreadful way to start.
Murray nailed a backhand winner to bring up three match points and took the second when a tired-looking Tsonga placed a backhand long after two hours and 35 minutes.