Daniil Medvedev progressed to the fourth round of the US Open with a 6-2, 6-2, 7-6 (8/6) victory over Sebastian Baez which snapped the Argentine's 12-match winning streak.
Third seed and 2021 champion Medvedev is through to the second week in New York for the fifth year in a row and will play Australian 13th seed Alex de Minaur for a spot in the quarter-finals.
Medvedev closed out the victory with an ace on his fourth match point in the tie-break as he finished well past 1am for the second straight match.
"I just want to go to sleep, that's it. Nothing more," said Medvedev.
"When you go to play at 11pm it just feels tough. This time I decided not to sleep before and I ate, so I was feeling pretty bad on the court. That's why I was nervous all the match."
World number 32 Baez came into the US Open bristling with confidence after titles at Kitzbuehel and Winston-Salem, reaching the third round of a Grand Slam for the first time here.
However hard-court specialist Medvedev -- winner of four titles on the surface this season -- started quickly and rarely looked in trouble as he took the first two sets with minimal fuss.
Baez refused to meekly accept his fate and threatened to force a fourth set.
He led 5-2 only for Medvedev to break back and then save a set point on serve, the Russian finally getting through in the tie-break in the early hours of Sunday morning.
"It was lucky and good play from me to stay in third set, and good not to finish at 4am."