Andy Murray overcame a confident start by young American wildcard Emilio Nava to reach the US Open third round for the first time since 2016.
Britain's Murray missed chances before losing a long first set but fought back to win 5-7 6-3 6-1 6-0 in New York.
The 35-year-old, who plays Italian 13th seed Matteo Berrettini next, is joined in the last 32 by Jack Draper after the Briton stunned Felix Auger-Aliassime.
Draper, 20, beat the Canadian sixth seed 6-4 6-4 6-4 in impressive fashion.
But compatriot Harriet Dart was unable to seal her place in the next round after losing 6-4 6-0 to Hungary's Dalma Galfi.
Cameron Norrie and Dan Evans could also move into the men's third round on Thursday, but there are no British women remaining in the singles after Emma Raducanu lost at the first hurdle of her title defence on Tuesday.
Murray uses experience to deflate Nava
A deep run at a major tournament has long been one of former world number one Murray's biggest targets, with the Scot's body eventually starting to hold up for longer periods than recent seasons.
Since having the hip surgery that he feared could end his career in 2019, Murray had only reached the third round at a Grand Slam event once when he lost to Canada's Denis Shapovalov at Wimbledon in 2021.
Eventually he reached the same stage again at Flushing Meadows, where he won his first major title in 2012, after wearing down Nava.
"Physically this is the best I've felt in the past few years," Murray said.
"My movement is by far the best it has been in a long time and it has obviously been a big part of my game.
"I feel like I'm getting closer to where I want to be."
Murray moved into the second round with a comfortable win against 24th seed Francisco Cerundolo, which was the first time he had won a match at a major in straight sets since 2017.
But 20-year-old wildcard Nava had to come through a gruelling five-setter and their contrasting energy levels eventually proved a key difference.
Before Wednesday's match on Arthur Ashe Stadium, Murray revealed he had practised with Nava earlier this week and said it was helpful to get a feel of his soon-to-be opponent's ball.
But he must have still been surprised by world number 203 Nava's level in a marathon first set.
After failing to serve out at 5-3, Nava clinched an 84-minute opener by breaking Murray's serve again from deuce at 6-5, thanks to a pair of stunning forehand winners from deep in the court.
The next question was whether Nava - making his debut on Ashe - could maintain a high level that was way above his ranking.
Quickly it became apparent he would not. Murray was encouraged by a dip of energy from Nava, breaking serve for a 3-2 lead in the second and never looking like he would relinquish the advantage.
The dominance continued into the third set and the three-time major champion, using all his experience and know-how to force mistakes from Nava, won 17 of the final 19 games.
"I think I started to take the ball on a little bit more, he was dictating a lot of the points," Murray said.
"I started to hit the ball deeper and I think his level dropped a bit. But he's a brilliant young player and he's going to have a very bright future."
Draper advances with biggest win of career
Late into the night, Draper continued his brilliant US Open debut with a remarkable win over Auger-Aliassime in which the Briton's serve was never broken.
The rising star of British tennis, Draper had already toppled players like Stefanos Tsitsipas and Dominic Thiem earlier in August and he made light work of his meeting with Auger-Aliassime on Louis Armstrong Stadium, one of the biggest stages in his sport.
He broke his opponent's serve in the opening game, capitalising on 2021 semi-finalist Auger-Aliassime's errors before saving three break points to serve out the first set.
Auger-Aliassime, ranked eighth in the world compared to Draper's 53rd, was completely outplayed by the young Briton, who has risen more than 200 places in the rankings in the past year and this win will earn him a place in the top 50 for the first time.
Victory puts Draper into the third round of a Grand Slam for the first time, where he will face Russian 27th seed Karen Khachanov.
"I have put in a lot of hard work the last few years. I have been a bit unfortunate with injury at a young age," Draper said. "I played a really good match today."
Dart cannot back up first-round performance
Dart impressed in her first-round victory against 10th seed Daria Kasatkina, but could not follow Murray into the third round.
The 26-year-old - who would have replaced Raducanu as British number one had she won - is ranked three places higher than Hungarian opponent Galfi at 88th in the world, but was outplayed on court 12.
Galfi broke Dart's serve in the first game of the match and raced to a 4-0 lead.
The Briton fought back, claiming a break herself to get to 5-3, but Galfi was able to hold on to take the first set.
The second was not as competitive and Dart looked visibly upset as she struggled to find any way to penetrate Galfi's game as the Hungarian rushed to what was in the end a comfortable victory.