Daniil Medvedev has joked about the longevity of Novak Djokovic, saying he might stop when he reaches 45 years old as both players prepare for the US Open.

36-year-old Djokovic is showing no signs of slowing down as he goes into the last Grand Slam of the year at Flushing Meadows. The Serb has won two out of the three majors to have taken place so far this year, lifting the trophy at both the Australian Open and the Roland Garros.

The latter victory saw him move past Rafael Nadal to achieve 23 major titles, the most of any men's singles player. Moreover, Djokovic has won 11 of the 22 Grand Slams that he has participated in since turning 30, suggesting he may only be getting better with age.

Ahead of the US Open, Medvedev joked about Djokovic's longevity.

"Him being back [at the US Open] is great. I always said I want him to play every tournament, especially even if at the moment he seems super young, there's going to be one moment, we don't know when, 45 years old, 40 years old, he's going to stop. I think that's the reality. I don't think he's going to go more than 45 years old or something," he said.

The world No. 3 also said that Djokovic is 'probably the greatest of all time' in the sport.

"So before he stops, it's great to see him play in every tournament. Out of let's say out of the big three, I played Roger [Federer], I was not the same as I am right now, my game matches Novak's the best. He's still probably the greatest of all time. It's great that I can give him hard time," he added.

Medvedev successfully defeated Djokovic in the US Open final two years ago to claim his only Grand Slam title to date. Reflecting on that day, the 27-year-old said he played some of the best tennis of his life. He also stated that he would like to achieve that success again.

"Two years ago I managed to play definitely one of, if not the best, match of my life. I want to try to do it again. He's other part of the draw, so let's see," he said.