The win was the Tsitsipas' third straight over a top 10 opponent after he dispatched Dominic Thiem and Novak Djokovic in the previous two rounds
Greek tyro Stefanos Tsitsipas' dream run at the Rogers Cup continued on Friday as the teenager toppled defending champion Alexander Zverev 3-6 7-6(11) 6-4 to reach the semi-finals in Toronto.
The win over world number three Zverev looked unlikely when the 19-year-old dropped the first set and fell behind 2-5 in the second.
But Tsitsipas managed to save two match points and shifted the momentum after edging Zverev in a marathon second-set tiebreak.
Extending the match paid off for Tsitsipas as Zverev made a number of uncharacteristic errors in a tight third set and he handed the world number 27 victory with a double fault on match point.
WHAT A WIN!— Rogers Cup (@rogerscup) August 10, 2018
Stefanos Tsitsipas' dream run continues in Toronto! He saves two match points to defeat Alexander Zverev 3-6, 7-6(11), 6-4 and reach his first Masters 1000 semifinal #RogersCup pic.twitter.com/2umKWLp5we
The win was the Greek's third straight over a top 10 opponent after he dispatched Dominic Thiem and Novak Djokovic in the previous two rounds.
"I'm confused now, is this real?" Tsitsipas said. "This shows that with dedication and work, dreams do come true."
Zverev, 21, was accused of poor sportsmanship after he failed to congratulate his opponent when speaking to reporters after the match.
"I don't think he played that well. I think the match was absolutely pathetic on all levels," the German said.
"I'm very honest with you guys. Today was an absolute pathetic match I don't even think he played well."
Next up for Tsitsipas is a showdown with big-serving South African Kevin Anderson, who thrashed Bulgarian Grigor Dimitrov 6-2 6-2 earlier on Friday.
Fourth seed Anderson, runner-up at Wimbledon last month, was never broken and won 81 percent of his first serves.
"As I’ve gone along, I’ve been able to trust myself more and more. Some of the results I’ve had definitely makes that process a lot easier!"— Rogers Cup (@rogerscup) August 10, 2018
Read what else @KAndersonATP had to say after reaching the #RogersCup semifinals: ⬇️https://t.co/TJHGbdjd3Q
Top seed Rafa Nadal came from behind to send hard-hitting Croatian Marin Cilic packing with a 2-6 6-4 6-4 win in their quarter-final match.
The world number one was far from his best but took advantage of 43 unforced errors by Cilic, who converted just three of his 14 break-point opportunities.
"It is a very important victory. The match became so difficult," Nadal said.
"It's a very good victory against a big opponent. It's confidence and another chance to play again tomorrow and that's great news. I'm excited about it."
"The way that he played in that first set was unstoppable, no? So I resisted. I play with the right tactic. I tried to find my solutions, but it was so, so difficult."— Rogers Cup (@rogerscup) August 11, 2018
Read more from Rafa's post-win presser: https://t.co/GU6Dko5Ici
Nadal will face Russian Karen Khachanov, who defeated Dutchman Robin Haase 6-3 6-1 earlier in the day behind 11 aces in a match that lasted less than an hour.
Nadal has won all three of his prior meetings with Khachanov including a straight-sets win in the round of 16 at the Monte-Carlo Masters in April, a tournament the Spaniard went on to win.