Boris Becker has told the young pretenders to step up their game and start beating the big three of men's tennis to grand slam titles.
Rafael Nadal's 12th victory at the French Open on Sunday made it 10-straight slams won by Nadal, Novak Djokovic and Roger Federer, and an unprecedented 11 won by players aged over 30.
Since Nadal won his first title at Roland Garros in 2005, Andy Murray, Stan Wawrinka, Marin Cilic and Juan Martin Del Potro are the only players to have broken the big three's dominance, and all have now passed their 30th birthdays.
At 25, Dominic Thiem is hardly a newcomer but he has at least made his mark at slam level, reaching two-successive French Open finals and taking a set against Nadal on Sunday.
Thiem defeated Djokovic in the semi-finals in Paris while Stefanos Tsitsipas has been making rapid strides and beat Federer at the Australian Open.
Thiem remains the only man younger than 28 to have reached a slam final, and Eurosport pundit Becker said: "That is not good. That is not a compliment for anybody under 28.
"And don't give me that the others are too good. We should question the quality and the attitude of everybody under 28. It just doesn't make sense. As much as I respect Roger, Rafa, Novak – who else? Show up. Give me something I want to talk about.
"Eventually they will be too old. But you want to see the passing of the torch while they are still in their prime. You want to see Stefanos and Dominic beating them when they are still very, very good.
"It's not the forehands. It's not the fitness. It's a certain mentality, mindset, attitude that makes the difference between winning and losing."
Federer, Nadal and Djokovic are widely considered the three greatest male players to have picked up a racket, with 53 slam titles between them, and their powers do not appear to have diminished in their 30s.
But Becker, who famously won Wimbledon at 17, does not think too much leeway should be given for the youth of the likes of Tsitsipas, Alexander Zverev and Denis Shapovalov.
"Already the 20-year-old Novak was very, very good," said the German. "Rafa won here at 19. Yes, in order to stay at the very top you have to improve. But they were always good.
"Novak at 20, you could see it was a question of time. And then he did win his major at 20. Don't give me you're too young for that. You're either good or not good."
The ATP has recognised for some time that it will face a huge challenge to keep its current levels of popularity once the big three retire given their all-encompassing dominance.
The introduction of the Next Gen Finals tournament for the best players aged 21 and under was part of an effort to make stars of the up-and-coming generation, but the global appeal of Federer, Nadal and Djokovic will be impossible to replicate.
Becker said: "There will be a dip. People have to get used to the new players. There will be a 'wow' moment. 'Wow, we're not talking about Roger and Rafa any more'.
"But we said the same thing with (John) McEnroe and (Jimmy) Connors, (Andre) Agassi and (Pete) Sampras. Maybe myself and (Stefan) Edberg and (Mats) Wilander.
"Tennis will always continue with great new stars. But there will be a dip and then the spotlight will be on the young generation to say, 'Now, show up. Who are you? Are you good enough, can you carry the sport, or was it all a bluff'?"