"I thought I found pretty good accuracy and angles with the first serve, and also my second serve worked pretty well".
A confident Tsitsipas sent a blistering forehand to the back corner while the ninth-seeded Serbian was heading the other way on his first match point to secure the win before looking at his box in disbelief.
Tsitsipas upset Novak Djokovic 6-3, 6-7 (5), 6-3 in third-round play at the Rogers Cup in a thrilling battle between one of the Tour's top young guns and the reigning Wimbledon champion.
"I feel very proud for me, myself, and my country".More news: Yerry Mina completes Everton move
Djokovic, a four-time Rogers Cup champion, faded in the decisive set against the flashy 19-year-old, who played with poise and power on a warm, breezy afternoon at Aviva Centre on the York University campus.
Djokovic, 31, took 84 minutes on Wednesday to advance with seven aces and two breaks of serve while never facing a break point against Toronto-based wild card Polansky, the world number 121.
His trademark retrieving skills were on display throughout the match, but Tsitsipas used strong groundstrokes to push the pace and force Djokovic to fully stretch on several rallies.
However, Tsitsipas did well to break Djokovic for a 2-0 lead in the third set and never looked back.More news: Bowing to Israeli bullying, BBC changes Gaza killings headline
"I'm happy to see Stan playing well again". Milos Raonic of Canada was scheduled to follow Djokovic's win on center court, but that match was delayed by rain. "It's true that with my serve in the second set I had some troubles but my return was working well.it was more about the mistakes from the baseline in my opinion".
Tsitsipas will face second-seeded Alexander Zverev of Germany, the defending champion coming off a tournament victory last week in Washington that included a semifinal win over Tsitsipas. "So just all in all, it wasn't that great of a match".
Eighth-seeded John Isner, the American who won at Atlanta two weeks ago, beat France's Pierre-Hugues Herbert 7-6 (3), 6-2.
Sixth seed Marin Cilic continued his quiet progress, beating Argentine 11th seed Diego Schwartzman 6-3, 6-2.More news: Melania Trump's parents become U.S. citizens
Dimitrov beat Frances Tiafoe of the United States 7-6 (7-1), 3-6, 7-6 (7-4). Dimitrov, who last reached a quarter-final in April, added: "Clearly I'm not playing my best tennis, but I'm finding a way and managing to go through those matches". Haase beat Mikhail Youzhny of Russian Federation 7-5, 6-2.