Alexander Zverev upset Djokovic to claim the biggest title of his career. The Greman registered a 6-4, 6-3 victory over Djokovic in one hour and 21 minutes. Zverev became the youngest champion of the ATP Finals since Novak Djokovic claimed the first of his five titles a decade ago, and the first from Germany since 1995, when Boris Becker defeated Michael Chang in the season-ending event.