Novak Djokovic produced another trademark comeback on Sunday, defeating top seed Alexander Zverev 4-6, 6-4, 6-4 to reach the China Open semifinals in Beijing. The six-time champion, competing at the ATP 500 event for the first time since 2015, was pushed hard by Zverev but recovered from a slow start to extend his unbeaten record at the tournament. Zverev Takes Early Control Djokovic struggled to find his rhythm in the opening set as Zverev used his powerful serve and groundstrokes to take control.