Coco Gauff won the final 10 games of her match against Elise Mertens, completing a 3-6 6-3 6-0 comeback and reaching the US Open round of 16, where she will face Caroline Wozniacki on Sunday.
The American appeared in big trouble at the outset of the match as the Belgian smartly changed up the pace of her shots to frustrate the teenager, who was broken for a second time when her forehand went long on set point.
Mertens relished her opportunity to play the spoiler in front of a sold-out Arthur Ashe Stadium crowd firmly in Gauff's corner, quieting the increasingly tense fans with a shush finger after smacking winners.
After some exchanges of breaks early in the second set Gauff seized the momentum for good when she broke for a 4-3 lead, pumping her arms and pointing to her ear when her backhand winner leveled the contest at a set apiece.
The third set was all one-way traffic as Gauff's speedy defense, pinpoint serving and terrific play at the net overwhelmed former two-time quarterfinalist Mertens.
Next up for sixth seed Gauff is an enticing first meeting with returning veteran Wozniacki, who came from behind in similar fashion and by a similar score line earlier in the day to see off American Jennifer Brady 4-6 6-3 6-1.
"It's a matchup I never thought I'd have to play," Gauff said of former world number one Wozniacki, who retired in 2020 to start a family and returned to the game last month.
"When she retired I remember saying that I wish I could have played her. So that wish came true so I'm really excited.
"I don't know if it's a battle of generations," she said of the matchup between Gauff, 19, and the 33-year-old Dane.
"She's still fit and going strong. I think it's going to be an exciting match."
Romanian Sorana Cirstea sent big-hitting fourth seed Elena Rybakina tumbling out of the US Open with a thrilling 6-3 6-7(6) 6-4 victory to reach the fourth round at Flushing Meadows for the first time in her career.
Cirstea got off to a solid start, breaking former Wimbledon champion Rybakina in the fourth game of the opening set, and the seasoned world No. 30 continued to dictate points from the centre of the court while taking an early lead in the clash.
The 33-year-old, who had lost her previous two meetings with Moscow-born Kazakh Rybakina, pounced early in the second set but dropped serve immediately as her opponent found her range again with some blistering groundstrokes.
Australian Open runner-up Rybakina failed to make the most of two set points at 6-5 and squandered two more chances to draw level in the tiebreak before getting the job done with a crosscourt winner, to the delight of the Louis Armstrong Stadium crowd.
But Cirstea composed herself to take charge of the decider and went up 4-1 before staving off a late comeback attempt by Rybakina and closing out the contest with a decisive late break after a double fault from her opponent.
Up next for Cirstea is a meeting with Swiss Belinda Bencic.
