Watch highlights as Alexander Zverev defeats Novak Djokovic in straight sets to win the Nitto ATP Finals. Zverev said: 'It's quite astonishing, winning this title, beating two such players back-to-back, Roger and Novak, in semi-finals and final. It means so much. I'm incredibly happy and incredibly proud of this moment right now. I wasn't trying to overthink it. I just tried to go out there and enjoy the match as much as I can, enjoy the atmosphere, enjoy the moment. That's what I did.'