Novak Djokovic will go into the French Open amongst the favourites after winning three Grand Slam titles in a row.
The Serbian added the 2019 Australian Open to his Wimbledon and US Open triumphs in 2018 – and remains on course for a historic perfect season.
Despite that, Rafael Nadal will be confident of a victory at Rolland Garros having won in 11 of his 14 visits there.
“Other than one guy, sure, it’s always open,” Djokovic told Metro.
“I think Rafa always is a very clear favourite on any clay court in the world, and it doesn’t change. He’s still there.”
However, although Nadal has dominated on the surface since making his debut in 2003, Djokovic knows that the Spaniard’s fitness could be an issue.
He added: “I mean, obviously depends how he’s feeling physically.
“You know, I have seen him play here [at the Monte Carlo Masters, and it] seems like he’s fine.
“You know, if he’s physically fit, he’s definitely the No 1 guy, you know, on this surface without a doubt. And then, you know, after him it’s quite open.
“You know, I think [Alexander] Zverev has done very well on clay in the last few years. Dominic Thiem, of course. Roger is going to play, as well, this season.
“That’s great for tennis. I think it is pretty open.”
Djokovic has now won 15 Grand Slam titles, which is two fewer than Nadal.
The 31-year-old was asked what it would mean to beat his rival in France, and admitted that it is an ‘ultimate challenge’.
“Yes, I mean, for sure, beating Rafa in Roland Garros would be ‑ and he’s one of the ultimate challenges of the sport, as it is winning against Roger in Wimbledon, yeah,” Djokovic said.
“I have been fortunate to experience both, so, you know, it is quite a special feeling, because they have dominated those surfaces so much in their careers.”