Alexander Zverev denied Roger Federer a shot at a 100th career title with a 7-5, 7-6 (5) victory on Saturday to advance to the championship match at the ATP Finals.
Zverev, 21, is the youngest player to reach the final of the season-ending event since 2009 and the first from Germany since 1996.
Federer, 37, was seeking a record-extending seventh title, but was unable to cope with the pressure created by Zverev’s power and precision at the O2 Arena.
An inspired series of shots earned Zverev the first break points of the match in the 12th game and Federer sent a forehand wide to fall behind.
Federer broke for a 2-1 lead in the second set, but Zverev quickly composed himself to hit straight back in the following game.
Zverev then played a nerveless tiebreaker to set up a title decider with either Novak Djokovic or Kevin Anderson, who will play in the other semifinal later Saturday.