Coleman Wong’s historic US Open run ended in a five-set thriller against Andrey Rublev, who eventually prevailed 2-6 6-4 6-3 4-6 6-3.
Wong, 21, came through three rounds of qualifying to become the first man from Hong Kong to reach the main draw of a Grand Slam in the Open era.
He then defeated American Aleksandar Kovacevic and Australia’s Adam Walton to move to within one win of reaching the second week in New York.
Against Rublev, the world number 173 played “with no fear” as he won the first set, twice breaking the 15th seed in a run of four consecutive games.
Rublev responded by winning the second and third sets before Wong wrestled his way back into the match at the beginning of the fourth, converting the only break point of the set in the opening game to force a decider.
There, Rublev made the decisive break in the sixth game before closing out the win on his first match point.
“He played aggressively and with no fear – it was tough,” said Rublev, who will play third seed Alexander Zverev or Felix Auger-Aliassime next.
“I didn’t start well, he was all over me, and I needed to fight for every ball to turn it around. He was fighting until the end in the last game. I’m happy I was able to win and get to the next round.”
Elsewhere, 435th-ranked Swiss qualifier Leandro Riedi became the lowest-ranked man to reach the fourth round of a major since 2002 after Poland’s Kamil Majchrzak retired injured in the first set.
Riedi’s next test is eighth seed Alex de Minaur, whose third round opponent Daniel Altmaier retired midway through the fourth set when trailing 6-7 (7-9) 6-3 6-4 2-0.
Tenth seed Lorenzo Musetti progressed in similar fashion against fellow Italian Flavio Cobolli.
Cobolli, the 24th seed, injured his arm in a fall during the match and received treatment from the trainer three times before retiring in the third set, trailing 6-3 6-2 6-0.
Musetti will face unseeded Spaniard Jaume Munar, who beat Belgium’s Zizou Bergs 6-1 6-4 6-4 to advance to the second week of a Grand Slam for the first time in his career.