World No. 1 tennis player Novak Djokovic acknowledged the long-awaited "shift of generations" in men's tennis after receiving a resounding Italian Open quarterfinals defeat from 20-year-old prodigy Holger Rune.

The "Big Three" of Djokovic, Rafa Nadal and Roger Federer have dominated the ATP Tour for nearly two decades, but age and injury have been catching up with them in recent years.

Top seed Djokovic's 6-2 4-6 6-2 defeat by Rune on Wednesday means that for the first time in 19 years, neither the Serb nor the injured Nadal will play in the Rome final.

Djokovic, who has now lost two in a row to Rune, said the next generation of players led by world No. 2 Carlos Alcaraz is like a breath of fresh air for the sport.

"A new generation is here already," Djokovic told reporters. "Alcaraz is number one in the world from Monday he's playing fantastic tennis. I think it's also good for our sport to have new faces, new guys coming up.

"We've been saying for years that we can expect that moment to come when you have a kind of shift of generations.

"I'm still trying to hang in there with all of them. I still have the hunger to keep going. Let's see how far I'm going to play."

Nadal and Djokovic share the record for most men's Grand Slams with 22 titles each, while Federer won 20 before retiring last year, but the grueling Tour is taking a heavy toll on their bodies.

Nadal has not played since injuring his hip at the Australian Open in January and has missed the claycourt swing ahead of the French Open, where he is a 14-times champion.

Djokovic, who battled an elbow injury recently, called for the physio during his match against Rune and took a painkiller to get him through it.

When asked if Roland Garros would be the most open tournament in years, Djokovic smiled and said: "It depends if Nadal plays.

"But next to him, Alcaraz, Rune – these guys are right there in contention, some of the biggest favorites to win the title."