Top seed Alexander Zverev switched into survival mode to claim a milestone 500th ATP match win on Thursday, fighting back to beat Matteo Arnaldi 6-7 (5/7), 6-3, 6-2 at the Toronto Masters.
Germany's Zverev broke twice in the deciding third set to reach the fourth round of the US Open tuneup, converting his second match point to back up his defeat of the Italian ealier this year in Acapulco.
"It's a great achievement," Zverev, winner of 24 ATP titles, said of reaching 500 career match wins. "Not a lot of players reach this milestone.
"But I still want 500 more – maybe even more," he joked. "You always want to win as many matches as possible. I'm all about this."
Unable to gain the upper hand in an 82-minute first set, Zverev said his game improved as the minutes dragged on against 2024 Canadian semifinalist Arnaldi.
"I started playing better from the baseline and found my rhythm a bit. My backhand felt off but I was comfortable and happy with my level," added Zverev who next faces Francisco Cerundolo – a 6-3, 6-4 winner over fellow Argentine Tomas Echeverry.
Alex Michelsen reached a Masters 1000 fourth round for the first time with a 3-6, 7-6 (7/4), 6-4 upset victory over third-seeded Lorenzo Musetti.
The 20-year-old American survived nearly 50 unforced errors and converted just two of nine break chances, but it was enough to vanquish Italy's Musetti, a two-time Grand Slam semifinalist ranked 10th in the world.
"It feels really good," the 26th-ranked Michelsen said after finally converting his seventh match point.
"I've put in a lot of hard work and it's paying off a little bit. I was wondering when it would happen and I guess it is starting to happen right now.
"I returned really well today," he added. "I played offensive tennis and executed really well."
Michelson will face fellow American Learner Tien for a place in the quarterfinals. Tien beat compatriot Reilly Opelka 7-6 (7/3), 6-3.
Fifth-seeded Holger Rune advanced with an efficient 6-2, 6-4 result over Frenchman Alexandre Muller.
RUUD RALLIES
Eighth-seeded Casper Ruud shook off a slow start to beat Portugal's Nuno Borges 7-5, 6-4.
The Norwegian was playing only his fourth match since Roland Garros after missing Wimbledon because of injury.
Trailing 4-1 in the first set, Ruud thwarted Borges's two chances for a 5-1 lead, methodically lifting his game and taking control with a late break before earning the lone break of the second set for his 20th win of the season.
"I just crawled into the first set," said Ruud, who fired nine aces. "I was able to get back into it. One break and things can happen. I raised my return game and got more balls back into play.
"In the second set I got the break and served my way through."
Despite his sluggish start, Ruud was delighted to beat Borges after falling to him at Roland Garros in May.
"It was nice to get my revenge," said Ruud, who next faces 11th-seeded Karen Khachanov.
Khachanov, seeded 11th defeated US qualifier Emilio Nava 6-7 (6/8), 6-4, 6-1 to book his second Masters round of 16 spot this season.
Ruud and Khachanov last played in a 2022 US Open semifinal won by the Norwegian.