Rafael Nadal may be facing another injury setback at the Paris Olympic Games after his coach warned over the Spaniard's fitness.

The 22-time major champion is widely expected to retire at the end of this year, though is preparing for a final swansong at Roland-Garros, where he has won 14 titles.

Nadal is set to play in the singles and doubles tournaments of the Olympics, partnering current French Open and Wimbledon champion Carlos Alcaraz for the latter competition.

Yet his participation has become doubtful after coach Carlos Moya confirmed Nadal had cancelled his training session on Thursday due to a hamstring issue.

"It was a setback and we decided that today Rafa would rest and not train to recover," Moya said, as quoted by Spanish journalist Rafael Plaza.

"We are going to give ourselves 48 hours, we have to wait."

The 38-year-old is reportedly feeling soreness in both his left and right hamstring having pulled out of a scheduled practice session with Alexander Zverev.

Alcaraz had been partnering Nadal throughout the week during training on the clay courts of Paris, though the veteran's feature has now been thrown under a cloud of doubt.

Nadal is one of just two players to have won Olympic gold in both singles and doubles since the sport returned to the Games in 1988, doing so at Beijing 2008 (singles) and Rio 2016 (doubles).

In the singles in the French capital, Nadal has been drawn against Hungary's Marton Fucsovics in the opening round, and the prize could be a second-round date with long-term rival Novak Djokovic.

The calendar Grand Slam remains a "realistic goal" for Rafael Nadal, but he will not lose sleep over the holy grail in tennis as he prepares for Wimbledon.

That is the message from Carlos Moya, who is a former world number one and has coached Nadal since 2016.

Nadal made an incredible comeback at the start of 2022 from a foot injury that has plagued much of his career, winning the Australian Open before claiming another French Open crown.

The 36-year-old surpassed Novak Djokovic and Roger Federer in the men's all-time grand slam wins list with victory in Melbourne, with Roland Garros success representing his 22nd major title.

Nadal has repeatedly played down the prospect of winning all four men's majors in a calendar year, with Rod Laver the last to do so all the way back in 1969.

While the calendar Grand Slam remains on the cards, Moya warned Nadal is only halfway to completing the illustrious haul as the Spaniard heads to Wimbledon.

"It is a realistic goal, right now he is the only one that can achieve it this year," Moya told Eurosport Spain.

"It is the first time in his career that he is in a position to achieve it, but we see it as something far away, it is only halfway.

"At the moment he doesn't lose sleep, as a team few things keep us up at night and this is not one of them.

"We have to go little by little, it is not something that we talk about, it is not a primary objective, although we are not going to give up on it."

Nadal revealed in Paris that he intended to have radiofrequency injections to boost his hopes of competing at the All England Club, and he has undergone two courses of said treatment.

Wimbledon starts on Monday, a tournament that Nadal has won in 2008 and 2010, but he has not played there since reaching the semi-finals in 2019.

Nadal ramped up his preparations with a week training on grass in Mallorca before playing an invitation event at Hurlingham Club this week, where he faced Stan Wawrinka on Wednesday.

"We had a pretty good week of training in Mallorca, although the grass there is a bit different from London, maybe that's why it's taking a little bit for him to adapt to the grass in England," Moya added.

"Right now, the important thing is that he spends time on the court and that his foot is fine, little by little he will pick up the pace, we also hope that the draw will help, especially in the first games.

"At Wimbledon there can always be more surprises. Regardless of the player you get in those first rounds, what is dangerous is the type of opponent you get, you have to be careful with the sluggers.

"Now he has two important exhibition matches, my confidence in him for Wimbledon remains the highest. He is perfectly suited to grass."

Rafael Nadal was "practically lame" before he called an early end to his season and has been "stumbling all year round", coach Carlos Moya has revealed.

Former world number one and 20-time grand slam winner Nadal will miss the upcoming US Open but hopes to return in 2022, yet Moya says there are question marks over what the best course of treatment will be for the 35-year-old's foot problem.

In announcing his withdrawal from the rest of the campaign, Nadal declared a foot issue that he has been bothered by since 2005 was behind his decision.

The Spaniard took a break after losing a French Open semi-final to Novak Djokovic, skipping Wimbledon and the Olympic Games.

He attempted to make a return for the hard-court season but lost his second match in Washington to South African Lloyd Harris.

Moya, who was also briefly a world number one, said Nadal had managed to prolong a career that was in doubt 16 years ago, thanks to insoles and treatment.

"But this year the story has changed in many training sessions," Moya said. "He could not finish them and we had to change and ease intensity for the foot, thinking about the tournaments.

"He has been in pain for months and there comes a time when he cannot take it anymore. In the last match he played practically lame.

"The best thing was to stop, rest the foot and refresh the head."

Speaking to Spanish broadcaster Onda Cero's El Transistor show, Moya said: "It is not known where this injury comes from. There is a diagnosis but it is not clear which is the best treatment.

"Rafa's main objective is to regain sensations in his feet and in his head, because stumbling all year round has not helped him."