'The Big Three' Novak Djokovic, Rafael Nadal and Roger Federer are still on top of the men's game, but for how long? Serena Williams' coach Patrick Mouratoglou says the Next Gen are getting "closer and closer".
Daniil Medvedev sealed the biggest title of his career at the ATP Tour finals in London at the back-end of last year before going on to reach his maiden Grand Slam final in Australia where Novak Djokovic swept past him to claim his ninth title in Melbourne.
Three-time major semi-finalist, Stefanos Tsitsipas, is also part of the chasing pack which includes US Open runner-up Alexander Zverev, Andrey Rublev, Denis Shapovalov and Italian teenager Jannik Sinner.
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Speaking from his academy in Nice, which will also host eight of the top ATP players including Medvedev and Diego Schwartzman for the fourth edition of the Ultimate Tennis Showdown (UTS) from Monday, Mouratoglou said the margin at the top of men's tennis is getting smaller.
He told Sky Sports: "The Next Generation has not taken over yet, despite a lot of comments saying that they have. Every time I am interviewed, I say 'no'.
"Rafa and Novak are still at the top of the game. Very clearly, Novak is less interested in every tournament that is not a Grand Slam and his results show, but when he comes to the Grand Slams he is always there and it's the same with Rafa.
"For the moment, we can't say that the Next Gen are taking over. They're getting closer and closer, that's for sure.
"I think that Novak feels that the guys are getting closer and closer and it's probably stressful (for him), but they're at the top of their game. For how long? I don't know.
"Is the margin as big as before? Definitely not. The margin is getting smaller and smaller but I want to see a new generation guy win a Grand Slam, defeating them, which still hasn't happened yet."
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Mouratoglou discussed the race to win the most Grand Slams, the return of Roger Federer and his hopes of adding to his major tally this summer.
The Swiss great is currently tied with Nadal on 20 Slam titles, while Djokovic is just two behind on 18.
"Rafa knows in order to win the Grand Slams he needs to win the other tournaments because he's always been like this. Novak, I think it's obvious and regarding Roger, for sure, he's had a long injury that actually lasted much longer than what he expected himself," he said.
"He knows that he's going to be 40 this year. He can do anything else but focus on the Grand Slams, making his preparation completely Grand Slam focussed to give himself the best chance. It's more like Wimbledon focussed and then the other Slams and lastly Roland Garros."
The Frenchman also gave his prediction to win this year's French Open men's singles winner.
He said: "Every year when I'm asked about Roland Garros, I give the same answer. I say 'the only thing we don't know when Roland Garros starts every year is who Rafa is going to beat in the final. Everything else... we know."
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