Coach Patrick Mouratoglou has backed Serena Williams to be a major contender for the French Open title.
Williams fell just short again in her pursuit of a first Grand Slam crown for four years at the Australian Open in February, losing to Naomi Osaka in the semi-finals, and her next chance comes at Roland Garros next month.
Williams has not been beyond the fourth round at the French Open since returning to the sport in 2018 following the birth of daughter Olympia, but she has twice been forced to withdraw through injury.
Mouratoglou cited the 39-year-old's improved fitness as the key factor behind her impressive form in Australia and is looking to continue that work during the build-up to Roland Garros, which begins on May 23.
He said: "She did a tremendous effort before the Australian Open and was very much in shape, so this is something that we definitely want to keep and continue to improve because it's a key, and it's going to be even more a key on clay.
"I think she can really play very good on clay, she just has to be really very fit because on clay the serve is not as efficient and you have to work much more. Every rally is a fight. But I feel if she's really, really ready, physically 100 per cent, then she can be very dangerous on clay as well.
"The level is high but I still believe that, when Serena is 100 per cent at the top of her physical form, she can win any Slam."
Much was made of Williams' tearful exit from the Australian Open, where she abruptly left her press conference after a lingering wave to Rod Laver Arena.
The 23-time Grand Slam singles champion has not been seen on a match court since, pulling out of the Miami Open following dental surgery.
"She was extremely disappointed because she really felt like she was ready to win it, she was playing really, really good tennis," said Mouratoglou.
"It's always difficult to take some positives when you have a big disappointment like that, but there are some positives and I told her that her fitness was really great, and that's the key and we have to keep working like that."