Tennis news - ATP Finals: Stefanos Tsitsipas into semi-finals after beating Alexander Zverev

Zverev looked unbeatable on serve against Rafael Nadal on Sunday, but the German was broken in the eighth game after opting to serve and volley on a second serve, making a mess of a low volley and from that point on it was one-way traffic.

Tsitsipas was unrelenting as he broke early in the second before securing a double break to storm into a 5-2 lead over his German rival, before another excellent service game to love - topped off with an ace - sealed the set and match at the O2 Arena.

21-year-old Tsitsipas - the first Greek player to qualify for the elite eight-man season ender - now joins Dominic Thiem in the semi-finals.

Nadal and Zverev will fight for a spot in the last four on Friday, while Novak Djokovic and Roger Federer go head-to-head tomorrow, each needing a win to progress.