Rafael Nadal insists Novak Djokovic remains a major threat to his hopes of an 11th French Open crown.
Serbian Djokovic has struggled to find his best form during a difficult few months having undergone elbow surgery.
The former world number one is the 20th seed at Roland Garros, but he showed glimpses of his old self at last week’s Italian Open before bowing out to Nadal in the semi-finals.
Nadal, who has lost just twice in 81 matches on the red clay of Paris, is once again the heavy favourite to triumph.
But he said: “Novak is one of the best players of our history of this sport. My answer is he’s not coming back, he’s there always.
“Sometimes when you come back from injuries it’s difficult to play that well from the beginning, but he played a great event in Rome, and is no doubt one of the candidates to win here.”
Nadal, himself only recently back from a hip injury, went on to win in Rome and begins his French Open campaign against Ukraine’s Alexandr Dolgopolov.
“I feel good,” added the Spaniard, who is back at the top of the world rankings. “Of course after a very tough beginning of the season, with two injuries in the same place, it’s true I came back and played well.
“I have played a lot of matches and had good success since I came back. But every tournament is different, and here we are to try our best, to have good days of practice before the tournament starts, and try to be very competitive for the beginning.”
Alexander Zverev is another expected to challenge Nadal’s dominance, the 21-year-old German taking him to three sets in the Rome final and winning in Munich and Madrid this year.
Zverev is seeded second and faces unfancied Lithuanian Ricardas Berankis in round one.
“It’s obviously been a fantastic clay-court season for me,” he said. “Winning so many matches in a row was great coming in here.
“Obviously there are a lot of other great players playing here; Rafa, Novak and everybody. They are all getting on top of their game.
“This is a long tournament with a lot of hard matches. I’m not trying to think that, you know, I’m going to play Rafa in the final. That’s not how I’m thinking.
“I’m thinking about every single match. I’m thinking about how to beat Berankis in the first round. That’s my thought process right now.”