Stefanos Tsitsipas ended the 13-match win streak of Casper Ruud on Friday with a clinical 6-1, 6-4 win into the semi-finals of the ATP Toronto Masters.
A day after turning 23, the Greek world number three celebrated the birthday of his mother Julia, using the big day as inspiration on court.
"I'm proud of myself," the 2018 Canada finalist said. "I had it in my mind to try and make her proud today."
Norway's 12th-ranked Ruud has been on fire the past month, winning three European clay titles last month in as many weeks after going out in the Wimbledon first round six weeks ago.
Ruud, son of former ATP pro Christian Ruud, had defeated Tsitsipas on Madrid clay in May.
But the Greek seed had all the answers in Toronto as he denied Ruud a 100th career match win.
"My intentions were clear from the beginning," the winner said. "My instinct was to stick to the baseline.
"I'm super happy to be standing where I am right now. Sometimes I surprise myself with how well I can play."
Tsitsipas finished with 20 winners and 11 unforced errors in his 74-minute victory.
Ruud missed on an overhead at 4-all in the second set, giving Tsitsipas two break chances.
The third seed converted on the second and served out victory moments later, increasing his wins this season to a tour-leading 45.