Rafael Nadal's hopes of returning to Roland Garros for a crack at a 15th French Open title suffered a major blow on Thursday when the 37-year-old Spaniard was forced to withdrew from the Monte Carlo Masters.

The 22-time Grand Slam winner was expected to make his ATP Tour comeback in the Principality having not played since Brisbane in January.

"Unfortunately I have to tell you that I am not going to be playing in Monte Carlo. My body simply won't allow me," said the battle-weary Spaniard on social media.

The record 11-time Monte Carlo winner missed virtually all of the 2023 season through injury and has only played at the Brisbane International this season, where he felt a hip injury flare-up during his quarter-final defeat by Jordan Thompson.

That prompted his withdrawal from the Australian Open as well as Doha and Indian Wells, where he had first intended to make his comeback.

His one appearance since Brisbane came in an exhibition match against Carlos Alcaraz in Las Vegas in March where observers noted some discomfort in his back, which has evidently not cleared up.

"Even if I am working hard and making the maximum effort every day with all the will to play and compete again at tournaments that have been very important for me, the truth is that I can't play today," Nadal continued.

"You have no idea how hard this is for me to not be able to play these events.

"The only thing I can do is to accept the situation and try to look at the immediate future keeping the excitement and will to play in order to give me a chance for things to get better."

The claycourt specialist has dropped to 646th in the ATP rankings and was due to use a protected ranking of ninth to get into the main draw in Monte Carlo, the first clay-court Masters 1000 event of the 2024 season.

For much of his career, Nadal has used Monte Carlo as a springboard for the French Open, a Grand Slam event he has won a record 14 times and which he is still hoping to play in, perhaps for the last time.

The last of his 11 wins in Monte Carlo was in 2018 -- he fell at the semi-finals in 2019, the quarters in 2021 and missed the 2020, 2022 and 2023 editions.

Of those 11 wins, nine were followed by victory at Roland Garros.

"I'm sad, for the fans who won't have the chance to see him, but especially for him because this Monte Carlo tournament is really important for him," Monaco tournament director David Massey told AFP.

"I know he's done everything to be ready for the tournament, so we wish him the best," he added.

The latest withdrawal is bound to raise further speculation about Nadal's future.

The desire to get out on court is still there, especially on the red clay of Roland Garros, but his body, with over 20 years of wear and tear, looks likely to have the final say.

Nadal, who is in the habit of celebrating his birthday on June 3 during the French Open, may not be blowing out his 38 candles in Paris this year.