It is only a "matter of time" until Carlos Alcaraz is the number one tennis player in the world, according to Richard Krajicek.

At the age of 20, Alcaraz has already won Wimbledon and the US Open, becoming world number one in September 2022.

He was defeated in the quarter-finals of the Australian Open to kick off this year's grand slams, though, failing to win any of the three tournaments in which he has played in 2024.

However, former world number four Krajicek believes Alcaraz is on his way to becoming the best, despite dropping to number two in the world rankings.

"His potential is very high," said Krajicek, speaking to Stats Perform at the Rotterdam Open. "I think he's the future number one.

"I'm not saying anything special because he's beaten everybody. He beat Djokovic three times out of the last four times they played. He beat Medvedev from being two sets to love down, which shows how mentally and physically strong he is.

"So for me, it's a matter of time until he becomes number one. I think he can play on all surfaces, maybe clay is his worst surface but all the other surfaces you would say he's a title contender."

Very sad I had to withdraw yesterday after hurting my ankle We will do some tests to see the extent of the injury. Thank you for the support! Obrigado @RioOpenOficial

Getty pic.twitter.com/EhiwsOXZMA

— Carlos Alcaraz (@carlosalcaraz) February 21, 2024

With the 'Big Three' of Roger Federer, Rafael Nadal and Novak Djokovic already retired or nearing the end of their storied careers, there's been much discussion over who will fill their boots.

Alcaraz has already proved his abilities, while 22-year-old Italian Jannik Sinner claimed Australian Open glory to kick off this year having reached the semi-finals of Wimbledon in 2023.

Krajicek feels those two will lead the way for the next era of men's tennis, saying: "It's difficult to say who the next generation will be, but I think Alcaraz and Sinner will have a good rivalry. They already have played unbelievable matches.

"Of course, Alcaraz has already been number one, won two Grand Slams. Sinner is now slowly coming also to that level. He is number four, maybe number three after this week."

However, Krajicek has reservations over whether the likes of Alcaraz and Sinner can reach the legendary status of the 'Big Three'.

"To really have the same kind of rivalry, I don't know if that's possible," Krajicek added. "I mean, together, Federer, Nadal and Djokovic won 66 Grand Slams. That's incredible. In every Grand Slam, they were in the final or winning. It's just amazing.

"I don't know if it's possible to have two players or three players that basically win every Grand Slam they play. But I believe those two are going to be the two biggest names for the next couple years."