Ben Shelton threw down eight aces and produced three love games in the second set in dominating Zizou Bergs 6-3, 6-2 on Friday in reaching the fourth round of the ATP Montreal Masters.
Fifth seed Shelton, highest-ranked man remaining in a severely depleted field, improved his chance for a second straight title in Canada with the rout in 65 minutes.
The American profited from foot faults and double-faults from his Belgian opponent in advancing to a round of 16 for the first time this season.
"It was a good day for me, I managed the match well," said 23-year-old Shelton. "He came out serving extremely well. I had to make some adjustments.
"I found a way to break his serve and kept the foot on the gas when I got the lead."
Shelton will play for a repeat spot in the last eight when he faces Brazilian teenager Joao Fonesca, who defeated ninth seed Casper Ruud 7-6 (8/6), 6-3.
Fonseca recovered after a slow start, trailing the Norwegian 4-2 before fighting his way back into contention.
The youngster finished off the win after leading 5-2, claiming victory on a second match point winner into the empty court.
"It was not easy at the start. He was serving well," the Brazilian said. "I fought to finally get the win."
Fonseca said he learned much after beating Ruud at Roland Garros: "Playing with the big guys this year was really important for my development.
When it comes to Shelton, Fonseca said, "I think I'll be prepared. He's a nice guy. I don't need to say how good he is on court. I'm just trying to rest and be prepared."
Tallon Griekspoor followed up his defeat of top-seeded Roland Garros champion Alexander Zverev, with the Dutchman gaining late momentum and getting through a rough patch for a 3-6, 6-4, 6-3 defeat of Matteo Arnakdi.
The Italian French Open semi-finalist took early command before Griekspoor took motivation through player box instructions from Swedish coach Thomas Hogstedt and turned the match on its head.
World number 66 Griekspoor went up two breaks in the deciding set against the 2024 Canadian semi-finalist, lost one of them but broke back for victory in his third match point after more than two hours.
"Tennis is such a tricky sport. It's never over until the last ball is hit," AFP quoted Griekspoor as saying. "I tried to stay focused, I'm happy with how I managed.
"I've had a good level in practice but was not able to convert it to the match court. Today was not easy but I'm pleased after a win like this.
"I was far from my best but I'm happy I played myself into the match to win it."
Griekspoor will bid for a quarter-final place when he takes on Spaniard Daniel Merida, who put out Alex Michelsen 6-4, 6-7 (4/7), 6-1, saving two match points in the second set for the American.
Merida, who had never won a tour-level hardcourt match prior to this week, arrived in Canada after winning the Umag title on clay in Croatia last month.
Czech Jakub Mensik advanced past Terence Atmane 7-5 6-4, winning back-to-back matches for the first time since reaching the semis two months ago in Paris to break fresh ground in Canada.
He will next play Botic Van De Zandschulp, who beat Hubert Hurkacz 3-6, 7-6 (7/4), 7-5.
