Tennis news - Roger Federer, Rafael Nadal and Novak Djokovic 'not unbeatable' - Patrick Mouratoglou

In an interview with Greek publication Sdna, Mouratoglou described the trio as "the greatest players of all time" but still believes younger players "have the opportunity to beat them".

The trouble is, he notes, less established players would typically need to beat more than one of the legendary stars in order to actually win a Grand Slam.

The task faced by players such as Daniil Medvedev, Grigor Dimitrov and a player Mouratoglou has coached himself, Stefanos Tsitsipas, is huge but possible.

"They are the greatest players of all time, so it's not that easy," Mouratoglou said in the interview.

"Stefanos [Tsitsipas] beat them all. But in order to win a major, you need to probably beat all of the three in general, or at least two, although it did not happen in New York.

"And that's the toughest. You can beat one, but you usually have to beat another. They are not far away from doing it but they are not ready yet."

Clearly Tsitsipas and others are not too far off, but the challenge of beating perhaps more than one of the legendary trio at a Slam is still pretty formidable.

The last Grand Slam won by a player not named Federer, Nadal or Djokovic was back in 2016 when Andy Murray won Wimbledon and Stanislas Wawrinka triumphed at Flushing Meadows.

The US Open is typically regarded as the best opportunity for a less established player to spring an upset given its position as the final Slam of the calendar year with Marin Cilic winning in 2014 and Medvedev was close to taking Nadal to five sets in New York this year, but the Spaniard still had that extra gear when it really mattered.

In conclusion: the 'big three' may well still have another year or two of cleaning up.