TORONTO (AP) — Greek teenager Stefanos Tsitsipas pulled off another upset Friday at the Rogers Cup, saving two match points in a 3-6, 7-6 (11), 6-4 victory over defending champion Alexander Zverev.

Zverev, the second-seeded German star coming off a victory last week in Washington, double-faulted on match point to send Tsitsipas to his first ATP World Tour Masters 1000 semifinal.

"I kind of fooled him when I was on the court," Tsitsipas said. "I did some things that he didn't expect me to do."

The 19-year-old Tsitsipas beat seventh-seeded Dominic Thiem and ninth-seeded Novak Djokovic to reach the quarterfinals. He's the youngest player to beat three top-10 players in one tournament since Rafael Nadal — who also was 19 — in 2006 at Monte Carlo.

Tsitsipas will face fourth-seeded Kevin Anderson in the semifinals, trying to become the youngest to beat four straight top-10 players in an event since the ATP World Tour was established in 1990.

Anderson beat fifth-seeded Grigor Dimitrov 6-2, 6-2. In the night quarterfinals, Karen Khachanov beat Robin Haase 6-3, 6-1, and the top-seeded Nadal faced sixth-seeded Marin Cilic.

Zverev was upset with his play — and wasn't that impressed with Tsitsipas, either.

"I always say when the opponent played better, I'm probably one of the most honest guys on tour," Zverev said. "Today was an absolutely pathetic match. I don't think he played well. ... To be honest, we played three sets and all three sets should have been 3, 3 and 3," Zverev said. "If we would have played best-of-five, that's what the score should have been."

Tsitsipas struggled with a first-serve percentage of 47 percent, well below Zverev at 70 percent. But the teen converted all four of his break-point opportunities, while Zverev was five for 14.

"The level of tennis today, in my opinion, was not the highest — it was all right," Tsitsipas said. "People seemed to love it, loved the show and everything. I would say I played OK."

The Greek player is ranked a career-high 27th and is guaranteed to break into the top 20. With Zverev's loss, Juan Martin del Potro will jump to No. 3 when the new rankings come out Monday.