Stefanos Tsitsipas defeated his second seed in as many days at the Toronto Masters, stunning Wimbledon champion Novak Djokovic 6-3, 6-7 (5/7), 6-3 to reach the quarter-finals.
The Greek teenager, who turns 20 on Sunday, followed up his defeat of seventh seed Dominic Thiem, beating four-time champion Djokovic, seeded ninth, in a first-time meeting.
"This was the best match of my career," Tsitsipas said. "I knew I was playing pretty good today.
"Losing the second set, it was tough to deal with - I had my opportunities and didn't use them.
"But I remained calm, I tried few things that I didn't try before. (The early break in the third set) was everything. It gave me the win at the end."
"I didn't return well. It wasn't that great of a match."
"I was really not focusing on winning or losing, just on starting to play good tennis and start building the right habits."
"I think I'm improving. With each game, with each point that I play, I feel more confident, more stable on the court, and everything falls into its place."