London: Stefanos Tsitsipas coasted past defending champion Alexander Zverev in straight sets to advance to the last four of the ATP Finals on Wednesday after Rafael Nadal came back from the dead to keep his title hopes alive.
The Greek tyro, 21, broke his big-serving German opponent three times in the Group Andre Agassi match to seal a 6-3, 6-2 win at London's O2 Arena.
The straightforward victory, which took Tsitsipas's head-to-head record against Zverev to 4-1, was in sharp contrast to the earlier match, in which Nadal produced an astonishing comeback to beat Daniil Medvedev.
AWESOME performance from @StefTsitsipas 🙌
The Greek defeats Zverev 6-3 6-2 to guarantee his place in the semis at the #NittoATPFinals 👌November 13, 2019
The Spanish top seed was on the brink of defeat when facing a match point at 5-1 down in the deciding set but stormed back to win 6-7 (3/7), 6-3, 7-6 (7/4).
"Today is one of those days that one out of 1,000 you win and it happened today," said a delighted Nadal.
The 19-time Grand Slam champion, who also beat Medvedev in the US Open final, said earning a break back in the deciding set had infused him with confidence.
"When you have the first break, 5-3, then you are only one break away," he added.
"And I know from my personal experience how tough it is to close out matches, especially when you have two breaks in front and you lose the first one. From that moment I thought I can have a chance."
Tsitsipas grabbed the contest by the scruff of the neck at end of the first set, breaking Zverev in the eighth game and served out for the set.
The Greek then broke in the opening game and the fifth game of the second set as Zverev struggled to produce the same level of tennis that propelled him to victory against Nadal on Monday.
"I was really surprised by my performance today," said the sixth seed, who beat Medvedev earlier in the week and who is yet to drop a set in London on his tournament debut.
"I did everything right and once again it was not just me out there but a whole bunch of people, excited people that came to support me. It was a crew situation."
The second semi-finalist from Group Andre Agassi will be decided on Friday.
Dominic Thiem has already secured one of the qualification spots in Group Bjorn Borg, leaving Federer and Djokovic to scrap it out on Thursday for the remaining place from the four-man pool.