The world No. 1 produced a stylish display to win 6-3 7-6 (7-4) against his 23-year-old opponent who struggled to reach the intensity needed to trouble the Serb.
Both men knew the winner of their final round-robin match would face reigning US Open champion, Dominic Thiem, in the semifinals on Saturday and Djokovic is well aware of the challenge ahead.
“Being one of the hardest workers on the tour, one of the most dedicated players, Dominic (Thiem) has found his A-game on all surfaces. His first grand slam came on a hard court earlier this year in New York,” Djokovic said after his match.
“I played him last year here and I lost … it was really a thrilling match. Hopefully, we can have another great match but hopefully with a different outcome.”
Having lost his last group match in straight sets to Daniil Medvedev, Djokovic started on the front foot and cruised to a set lead with relative ease.
However, Zverev began to find his rhythm as the match progressed and his first serve began dominating proceedings.
But it was a case of too little too late for the 2018 champion as Djokovic expertly held his nerve in the second-set tiebreak — the Serb has only lost one tiebreak this season.
“I felt great, early in the first set he had a couple of breakpoint chances but I managed to serve well in the important moments,” Djokovic added.
“Contrary to the last match against Daniil (Medvedev) I just managed to find the right shots at the right time.
“I have tremendous respect for him (Alexander Zverev). He’s a great player, huge serve, Obviously, it’s not easy to return the 140mph serves.”
An in-form Medvedev will face Rafael Nadal in the other semifinal on Saturday with the season-ending finale set for Sunday.
Nadal has won 20 grand slams during his illustrious career but has yet to win the ATP Finals.
The tournament is being held at the O2 Arena in London for the last time before it moves to Turin in 2021.
There won’t be a chance for fans to say farewell to the stage that’s hosted the Finals since 2009, with matches being played behind closed doors due to the pandemic.