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) victory on Monday.
Anderson is the first South African in New York's last 16 since Wayne Ferreira in 2002.
The 15th seed, who had lost the seven previous times he 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 tie-break 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 hard-court 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 and 2013 Wimbledon champion.
Murray had 49 winners and 20 unforced errors, but did not make a forehand winner until the last game of the second set.
Anderson blasted 81 winners to 57 unforced errors.
He ripped a forehand winner on the final point of the opening tie-break to take the set after 69 minutes, then broke Murray's first service game of the second set on the way to a 5-1 edge.
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.