New York - Third seed Stan Wawrinka saved a match point to defeat Britain's Dan Evans 4-6, 6-3, 6-7 (6/8), 7-6 (10/8), 6-2 and reach the US Open fourth round on Saturday.
The 31-year-old Wawrinka, a semi-finalist in 2013 and 2015, saved the match point at 5/6 down in the fourth set tiebreak to break the will of his 64th-ranked opponent in a four-hour epic.
Wawrinka will play either Australia's Nick Kyrgios, with whom he has a bitter personal rivalry, or Illya Marchenko of Ukraine for a place in the quarter-finals.
"I was lucky to get through, saving match point," said Wawrinka, who is in the last 16 in New York for a fifth successive year.
"He has great talent. I'm just happy to get through."
Wawrinka finished with 12 aces and 58 winners but the most important shot was the nerveless forehand volley he played to save the match point.
His greater experience told in the decider -- it was Wawrinka's 43rd five-set match compared to Evans's fifth.
The Briton called for the trainer at 1-4 down but was furious when the physio decided he was suffering cramp and not a physical injury and so refused to treat him.
Should Wawrinka face Kyrgios on Monday it will rekindle memories of their bitter clash in Montreal last year when the fiery Australian made a lewd, sexual slur at the Swiss star's girlfriend Donna Vekic.
Kyrgios was fined and handed a provisional suspension for the outburst.
They have played twice since with Wawrinka winning in Dubai this year before Kyrgios triumphed in Madrid.