Novak Djokovic on Tuesday said Rafael Nadal was his favourite to win the French Open, despite the record 14-time champion struggling for fitness in the twilight of his career.
World number one Djokovic is tuning up at the Geneva Open this week before the second Grand Slam of the year begins in Paris.
He said if Nadal was in the French Open draw, he could not be ruled out, despite his injury problems and growing competition from a younger generation.
"This year is more open," French Open defending champion Djokovic told reporters at the Parc des Eaux-Vives grounds in Geneva.
"Casper Ruud is surely one of the five players who are candidates to win. You have Alexander Zverev, Andrey Rublev, Stefanos Tsitsipas -- all the players who won a major tournament on this surface this year.
"But when you talk about Roland-Garros and Nadal is there, he is always the biggest favourite for me.
"After everything he has done on the courts at Roland-Garros, it's normal, respectfully to put him as the biggest favourite.
"Obviously it's a little different with his level of play. But it's Roland-Garros, and it's Nadal.
"After that, maybe me, if I feel good, if I play well. At Roland-Garros, and all the Grand Slams, I am a bit of a different player."
Djokovic, who turns 37 on Wednesday, took a wild card to play in Geneva in a bid to rescue an alarming dip in form ahead of his French Open title defence next week.
The 28-man Swiss clay court tournament serves as a final warm-up.
The record 24-time Grand Slam champion will arrive in Paris without a title in the season for the first time since 2018, unless he wins Geneva.
Search for form
While time has caught up with 37-year-old Nadal, Djokovic said he was hungry to keep playing at the top.
"I'm searching for my highest possible level," he said.
"It's not an obligation. It's truly my desire, my feeling, my passion, my love for tennis. That's the most important. I'm seeking to stay connected with that feeling."
Djokovic said he knew Geneva well as he has cousins in the Swiss city, though he has never played at the Geneva Tennis Club before.
"At this moment, there is no better practice for me than match play. So I feel like I need more matches," he said.
"That's the way for me to try to find the kind of form that I need for Roland-Garros."
Djokovic was at the Stade de Geneve on Monday to witness Young Boys winning a 17th Swiss football championship with a 1-0 victory over hosts Servette -- a team the Serb has a long-standing fondness for.
Djokovic said one of his cousins was set to marry a Servette player -- French midfielder Timothe Cognat, according to Swiss media.
Djokovic's best friend, and best man at his wedding, was defender Neven Markovic, who played for Servette from 2013 to 2015.
"That's why I'm supporting the club," Djokovic said, jovially adding that Markovic could perhaps best be categorised as a "very physical player".
"I'm not a football expert -- but he's a crazy guy," he said.