This victory, achieved in two hours and 35 minutes, allowed Djokovic to set a new record for the most consecutive wins from a debut at a single men's singles ATP Tour event in the Open Era. Previously, Rafael Nadal had won his first 31 matches at Roland Garros before his streak was halted by Robin Soderling in 2009.

On the Capital Group Diamond court, Djokovic secured the win by capitalizing on his few opportunities against an in-form Zverev. The German player hit 19 aces but lost his final service game in both the second and third sets. Two crucial breaks of serve while leading 5-4 were enough for Djokovic to turn the match around.

This marks Djokovic's second victory over a world's top two opponent this season, following his Australian Open semifinal against Jannik Sinner. He also became the third male player to defeat a top three opponent after the age of 39 since the ATP rankings began in 1973, joining Ken Rosewall and Jimmy Connors.

Djokovic shakes hands and embraces Zverev after his China Open quarterfinal victory on Diamond Court at the National Tennis Center in Beijing, China on 4/10. Photo: AP

Djokovic entered the match with health concerns, having required medical attention in his first two rounds. In contrast, Zverev had just defeated Shang Juncheng 6-0, 6-3 in 55 minutes. The top seed is having a season with two Grand Slam titles, at Roland Garros and the US Open, and is competing for the world number one spot.

The start of the match put Djokovic at a disadvantage. He committed two double faults and lost his opening service game. Zverev maintained that lead throughout the set, despite saving two break points while serving at 5-4.

"I started poorly. It was quite cold, and I felt I hadn't warmed up enough, but that's my fault", Djokovic said. "From the middle of the first set, I started to find my rhythm in my service games".

Djokovic maintained that consistency for the rest of the match, winning 82% of his first serve points. His ability to hold serve allowed the Serbian player to patiently wait for his chance, instead of constantly chasing his opponent.

His opportunity arrived in the 10th game of the second set. Djokovic returned serve effectively, allowing Zverev to win only one point before breaking his serve to level the match. In the deciding set, both players continued to hold serve until the score reached 5-4. Djokovic missed his first match point after a long rally but converted his second opportunity when Zverev hit a forehand into the net.

"I tried to attack, come to the net, and change the pace, avoiding repeating the same playing style", Djokovic said. "When he serves like he did tonight, opponents have few chances. I'm glad I stayed calm and played well at important moments".

The result improves Djokovic's head-to-head record against Zverev to 10-5. At the age of 39, Djokovic continues to protect his unbeaten record in Beijing, where he has won all six of his previous appearances. His next opponent is Daniil Medvedev, who just defeated Francisco Cerundolo 7-6(4), 6-3. The Russian player is on a seven-match winning streak, extending from his Hangzhou Open title. The other semifinal pairing is Alex de Minaur against Hubert Hurkacz.

Vy Anh