PARIS, June 5, 2025 (AFP) - Novak Djokovic said beating Alexander Zverev on Wednesday was a "testament" to his ability to compete at the highest level as the 38-year-old reached the semi-finals at Roland Garros to inch closer to a record 25th Grand Slam title.

Djokovic fought past third seed Zverev 4-6, 6-3, 6-2, 6-4 in a gruelling night session duel, which captivated Court Philippe Chatrier over three-and-a-quarter hours.

The 24-time Grand Slam winner moves on to face world number one Jannik Sinner in the last four, after the Italian earlier raced past the unseeded Alexander Bublik in straight sets.

"Jannik is in tremendous form, and he has been the best player for the last couple of years," said Djokovic.

"It's going to be of course semi-finals of a Grand Slam against the No. 1 in the world. There is no bigger occasion for me, so I'll try to do my best to step it up and perform as well as I did tonight.

"I just hope that I will be able to physically keep up, you know, with Sinner in few days' time. It's a big challenge for me."

On centre court, last year's runner-up Zverev roared out of the blocks with an immediate break of serve as he clinched the opener against Djokovic.

It was the first time former world number one Djokovic has dropped a set at the French Open this year.

- 'Forget the age' -

Djokovic engineered himself a 3-1 lead in the second set after Zverev pushed a backhand long when serving at 30-40.

The three-time Roland Garros champion then held firm through the rest of the frame to level the match as he started to punish the 1.98m-Zverev with drop-shots.

The Serb sniffed out a break opportunity in game five of the third set and snaffled it, before again breaking the German as he took control of the encounter.

Now on a high, Djokovic started the fourth by again pouncing on his opponent's usually reliable serve.

He brought Chatrier to its feet when he whipped a cross-court forehand past Zverev to save break point in the sixth game at the end of an exchange that the 28-year-old looked certain to win on at least three occasions.

Zverev appeared a defeated man when he eventually passed up that chance at a vital break-back with a netted forehand.

Djokovic marched on and sealed his 101st win at the French Open, raising his arms aloft in triumph after finally converting match point at the fifth time of asking.

"It was an amazing match," summarised Djokovic.

"Obviously beating one of the best players in the world on the biggest stages is something that I definitely work for, and I still, you know, push myself on a daily basis at this age because of these kind of matches and these kind of experiences.

"It's a proven kind of testament to myself that I can and to others that I can still play on the highest level."

A poor run of form earlier in the season and his advancing years had some questioning whether Djokovic could still match his younger rivals.

But he had a response for his doubters: "I think the win against (Carlos) Alcaraz in quarters of Australian Open (2025), to win quarters against Zverev tonight proves to myself and others that I can still play on the highest level, and I just thrive on these occasions."

A sentiment echoed by Zverev.

"I think at the moment he's a bit underrated, to be honest," Zverev said of Djokovic.

"I think like a lot of people count him out already, but this year he's had wins over Carlos at the Australian Open, he has had a win over me at the French Open. Forget the age. I think for any player, those are pretty good results."

Defeat at the quarter-final stage of the tournament in which he has reached at least the last four every year since 2021 brings an end to a disappointing clay-court season for Zverev.

The three-time Grand Slam runner-up endured early exits at the Monte Carlo Masters and Madrid Open, as well as in the last eight in Rome.