Novak Djokovic out-battled Alexander Zverev to qualify for the last four at the ATP Finals on Friday, staying on track to match Roger Federer's record of six titles at the end-of-season event. The Serbian top seed, who was beaten comprehensively by Daniil Medvedev in his second round-robin match, was again below his best in London but did enough to win 6-3, 7-6 (7/4). In the evening match at the elite eight-man event, which was a dead rubber, Russian fourth seed Medvedev beat debutant Diego Schwartzman 6-3, 6-3. In a repeat of the 2018 championship match, Djokovic saved all three break points he faced to gain revenge against the German, and will face Group London 2020 winner Dominic Thiem in the semi-finals.

Medvedev, who topped Group Tokyo 1970, will meet Spanish second seed Rafael Nadal in the other last-four clash at the empty O2 Arena. The group-stage results mean the four top-ranked players in the world will all be involved in Saturday's semis. Djokovic has already tied Pete Sampras's record mark of six year-end number-one finishes and is eyeing Federer's record at the season finale. The top seed broke Zverev at the first time of asking and raced into a 3-0 lead, threatening to run away with the match. The 33-year-old looked focused after his uncharacteristic mauling by Medvedev, serving himself out of trouble when he found himself trailing 15-40 in the seventh game. That proved to be the last chance for Zverev in the set and 17-time Grand Slam winner Djokovic hammered a backhand winner down the line to take it 6-3.