Novak Djokovic has beaten top seed Alexander Zverev 4-6, 6-4, 6-4 to reach the China Open semifinals. The 39-year-old extended his unbeaten run in Beijing to 32 matches.

Playing the ATP 500 event for the first time since 2015, the six-time champion was pushed hard by the reigning French Open and US Open champion.

Zverev took the first set with power tennis. Djokovic double-faulted twice in the opening game to hand over an early break.

The turning point came late in the second set. Djokovic broke at 5-4 to level the match. He struck again at 5-4 in the third to seal victory in two hours and 34 minutes.

The win set a record. Djokovic’s 32-0 start at a single tournament beats Rafael Nadal’s 31-0 start at Roland-Garros.

There was a flashpoint when the umpire replayed a point after Zverev complained about an LED screen flicker. Djokovic called it one of the “stupidest” rule calls.

Djokovic will face Daniil Medvedev in the semifinals. The Russian beat Francisco Cerundolo 7-6, 6-3.