Borna Coric and Denis Shapovalov produced incredible comebacks at the US Open, while Novak Djokovic eased into the last 16. (More Tennis News)
Coric and Shapovalov looked set for third-round exits at Flushing Meadows before fighting back for stunning wins on Friday.
Djokovic, meanwhile, had far fewer problems as he stayed on track for an 18th grand slam title.
There was also drama in New York before Alexander Zverev's third-round victory over Adrian Mannarino.
CORIC, SHAPOVALOV IN EPIC COMEBACKS
Coric was staring at an exit before responding to stun Greek fourth seed Stefanos Tsitsipas 6-7 (2-7) 6-4 4-6 7-5 7-6 (7-4).
Trailing by two sets to one, Coric – the Croatian 27th seed – fell 5-1 behind in the fourth against Tsitsipas on Louis Armstrong Stadium.
However, he saved six match points and won six consecutive games to force a decider.
After another thrilling battle, Coric came from a break down in the fifth set to reach the fourth round of a grand slam for the third time in his career.
Coric will next face Jordan Thompson after the Australian brushed past Mikhail Kukushkin 7-5 6-4 6-1.
Shapovalov also looked set for an exit against American 19th seed Taylor Fritz.
The Canadian 12th seed trailed 5-2 in the fourth set before recovering to win 3-6 6-3 4-6 7-6 (7-5) 6-2.
Shapovalov incredibly finished with 60 winners and 33 unforced errors to reach the fourth round of a grand slam for the second time in his career.
He will meet David Goffin after the Belgian seventh seed proved too good for Filip Krajinovic 6-1 7-6 (7-5) 6-4.
NO DRAMA FOR DJOKOVIC
Djokovic's comfortable run continued with a 6-3 6-3 6-1 win over Jan-Lennard Struff on Arthur Ashe Stadium.
The world number one improved to 26-0 in 2020 and he has dropped just one set through his first three rounds in New York.
Djokovic has now made at least the fourth round in his previous 13 appearances at the US Open, where he is a three-time champion.
The Serbian had won all four of his previous meetings with Struff, including twice this year, and he outclassed the German 28th seed again.
Djokovic will next face Pablo Carreno Busta after the Spanish 20th seed eased past Ricardas Berankis 6-4 6-3 6-2.
OFF-COURT DRAMA IN NEW YORK
Zverev's clash with Mannarino was delayed after health officials did not want the Frenchman to play.
Mannarino was one of the players put in a "bubble within a bubble" in New York after being in contact with Benoit Paire, who tested positive for coronavirus.
The Frenchman's third-round clash with Zverev was delayed before he was allowed to play, suffering a 6-7 (4-7) 6-4 6-2 6-2 loss to the German fifth seed.
Zverev moved into the fourth round, where Alejandro Davidovich Fokina awaits.
Davidovich Fokina got past Cameron Norrie 7-6 (7-2) 4-6 6-2 6-1.
