Stefanos Tsitsipas, 21, booked his trip to the semi-finals on Wednesday with a 6-3, 6-2 win against defending champion Alexander Zverev. Tsitsipas, who beat fourth seed Daniil Medvedev on Monday, improved to 2-0 in London and has yet to drop a set in his ATP Finals debut.

“It’s really good to know that I’ll be playing in the semi-finals, but I’ve got to concentrate, keep going the way I have been doing things the last couple of days,” Tsitsipas said.

The 2018 Next Gen ATP Finals champion strolled to his fourth win in five tries in his FedEx ATP Head2Head series against Zverev, keeping the German off-balance from the baseline and breaking three times in their Group Andre Agassi matchup.

Tsitsipas particularly pounced on the German’s second serve, which had been a problem spot for Zverev earlier in the season. The German won only 28 per cent (5/18) of those points.

“I always find an extra motivation, an extra reason to play well against the top guys. I consider Sascha also being of this part of this elite group,” Tsitsipas said.

Zverev, serving down 15/40, 3-4 in the first set, opted to serve and volley off a second serve, and Tsitsipas countered with a low return that Zverev miffed.

The Greek then broke in the opening game and the fifth game of the second set. Zverev struggled to bring the same level that helped him beat Rafael Nadal on Monday night and become the first player to beat the Big Three of Nadal, Novak Djokovic and Roger Federer at the Nitto ATP Finals.

“He played a fantastic match, I thought. I played really bad,” Zverev said. “At this level, this is how it goes when somebody plays great and you don’t play your best. It can go this way, especially against him who I think this surface, these conditions fit him quite well.”

Tsitsipas will next meet Nadal for a chance to go 3-0 while Zverev will face Medvedev in a match that will have semi-final implications.