Cameron Norrie capitalised on missed opportunities from Andy Murray as he reached the last 16 in Cincinnati with a 3-6 6-3 6-4 win.
Norrie won the all-British match in three sets, relying on his mental strength to survive a wave of aggression from Murray.
The three-time grand slam champion missed an array of opportunities as he once again suffered cramping issues towards the end of his defeat.
Norrie will play either Casper Ruud or Ben Shelton in the last 16 on Thursday.
After an exchange of breaks to start the match, it was Murray who took the initiative early on dictating play from the baseline with good shot selection.
Murray bounced back from wasting two break point opportunities in the fourth game as he grinded out the break in the eighth game, forcing some uncharacteristic errors from Norrie’s racket.
Although the British number one pushed for the break back, it was Murray who continued to pile on the aggression as he converted his second set point to hold and take the opening set 6-3.
Murray continued to dominate proceedings against an under-par Norrie in the second set and it would be the start of a frustrating theme for the three-time grand slam champion as he missed a plethora of break points.
In total Murray converted two of eleven break point opportunities as Norrie slowly grew into the match, hitting more confidently.
Norrie’s mix of variety and power saw him break in the eighth game as Murray was punished for passive play on big points.
The Brit missed three more break points in the next game as Norrie forced a deciding set.
In the final set both players produced their best tennis of the set as they produced accurate and smart serving.
As Murray continued to be clinical on serve but he couldn’t repeat the same feat on return as he missed simple forehands and groundstrokes to convert his break point opportunities.
Norrie took advantage of denying Murray the break in the sixth game as he went for the break in the ninth game.
Murray’s cramping issues would come back to haunt him as a double fault sealed the break for Norrie, with the ninth seed closing out the match with some spectacular tennis.
After the match Norrie admitted it was one or two points that was the difference between victory and defeat, “There were a couple in the second and third set as well, when he had a couple of break chances, and then I was able to play the bigger points a little bit better. It came down to one or two points and that was the difference,” Norrie told the ATP website.
“I just needed to put a lot of balls in the court. At the start of the match nothing was really working for me, I was not really being physical, I was not really executing how I liked.
“Credit to Andy, he came out and was using his slice a lot, coming forward well. He reads the game incredibly, so credit to him and it was not easy towards the end, I managed just to find a way.”
Norrie will look to play better when he takes on Casper Ruud or Ben Shelton on Thursday.
As for Murray he will look to improve his stamina and tactical play just in time for the US Open which starts on the 29th of August.