Alexander Zverev has made it to the last four at the ATP finals in London after defeating Danill Medvedev in straight sets.
Zverev broke in the opening game and put on a steady performance to earn the first set 6-4.
In the second set, Medvedev dug deep and sent the match into a tie break, but his double fault at 4-3 gave Zverev a 2-point lead, and the German served it out with an ace to finish second.
Zverev who is the defending champion will meet Group Bjorn Borg winner Dominic Thiem on Saturday, while Stefanos Sitsipas will face Roger Federer for a place in the final.