Djokovic stuns top seed Zverev at China Open

He "evidence to me that I can still beat the best players in the world on the biggest stage". "Things are a bit different nowadays. It's hard to be consistently playing on the highest level like the youngsters," he said.

He needed to play a mix of shots in "high-risk tennis" against the German, but he said feeling "physically pretty good" on the court after dealing all year with health issues helped him fight back. Djokovic got off to a poor start, double-faulting twice in the first game to help Zverev, a decade his junior, break serve instantly.

Boos filled the stadium soon afterward when the umpire agreed to replay a point Djokovic had won, after Zverev complained about a flicker in the LED panels during play. The German saw out the first set from there, but a valiant Djokovic roared back to seal the second with a cross-court winner to break serve and force a decider.

The 24-time Grand Slam champion faced 19 Zverev aces throughout the match but held steady on his own serve to go 5-4 ahead in the final set. He then broke the world number two to take the set and the match, seemingly defying his recent physical difficulties with victory in a gruelling two hours and 34 minutes.

Djokovic will face Medvedev in the final four after the former world number one dispatched Francisco Cerundolo 7-6 (7/4), 6-3. Poland's Hubert Hurkacz also advanced to the semi-finals after beating Karen Khachanov, and will play Australia's Alex de Minaur, who survived a gruelling test to beat Andrey Rublev 1-6, 6-2, 6-3.

Sabalenka swept out. Aryna Sabalenka was swatted aside in straight sets in the third round, leaving the women's draw without its top two seeds. Czech player Nikola Bartunkova, 20, sent down four aces to beat the former world number one 6-4, 6-3 in one hour and 35 minutes.

"I focused on myself, to be calm," 34th-ranked Bartunkova said. "She's a legend... so I'm really happy that I won the match," she said of the four-time Grand Slam champion. Bartunkova next faces Austria's Sinja Kraus in the round of 16.

A frustrated Sabalenka tossed her racquet at a break down in the fourth game of the second set, and lost on the first match point when she returned into the net. Top seed Elena Rybakina -- who replaced Sabalenka as world number one weeks ago -- is also out, having lost to Alina Charaeva in the second round.

French Open champion Mirra Andreeva of Russia set up a fourth-round match with Ukraine's Daria Snigur, while Wimbledon champion Linda Noskova breezed past Viktorija Golubic 6-2, 6-1. Noskova next faces 28th-ranked Russian player Ekaterina Alexandrova.

Naomi Osaka, the 2019 champion, beat Sara Bejlek and will face either Karolina Muchova or Liudmila Samsonova, scheduled to play each other Sunday night.