Third-seeded Andy Murray was knocked out of the US Open by big-serving South African Kevin Anderson, who reached his first grand slam quarter-final with a 7-6(5) 6-3 6-7(2) 7-6(0) win on Monday.
Anderson, the 15th seed who had lost the seven previous times he had reached the fourth round of a grand slam, finally came through on the strength of a big forehand and a brilliant display of serving against one of the game's best returners.
"I played one of the best matches of my career," said Anderson. "To do it at this stage, at this round, to get through to the quarter the first time in a slam definitely means a lot to me."
"It feels good to take a little step and actually beat one of the best guys in the world in the fourth round of a slam.
"Playing Andy, who is a champion here (2012) ... I must say playing out there will be definitely one for the memory bank."
Murray had battled his way back from two sets down in the second round against France's Adrian Mannarino, but the Scotsman could not work another miracle against the 29-year-old Anderson, who swept the final tiebreak 7-0.
The 6-8 (2.03m) South African finished with a flourish, cracking his 25th ace along with two other service winners in ending the match, the longest of the tournament, after four hours and 18 minutes.
Anderson was primed for his grand slam breakthrough, having won a hardcourt tournament in North Carolina before the US Open.
"I was playing against an excellent player. He served extremely well," said a disappointed Murray, who hammered in 19 aces himself in the Louis Armstrong Stadium clash.
Anderson, who won the first two sets in his fourth-round match at this year's Wimbledon before falling to eventual champion Novak Djokovic, refused to wilt against Murray, the 2012 US Open and2013 Wimbledon champion.
Murray stayed alive by clinching the third set tie-break 7-2 with a finishing ace, but Anderson trumped him by dealing a shutout in the tie-break to finally reach the quarter-finals.
The upset lifted Anderson into a last eight meeting against fifth-seeded French Open champion Stan Wawrinka of Switzerland, a 6-4 1-6 6-3 6-4 winner against American Donald Young.