Rafael Nadal in crisis? For the first time in history, the Superman of tennis looks human

Rafael Nadal is heading into this month's French Open in uncharted territory. A 13-time champion in Paris, if Nadal is competing, he is usually nailed on to be the bookies' favourite. Such is his level of dominance at the tournament, with 105 wins and just three losses, that a statue was erected in his honour last year. Beyond Novak Djokovic's challenge over the years, the Spaniard has been close to invincible on Paris's clay.

But on Friday, the morning after he limped out of the Italian Open, the markets put history to bed and reacted accordingly: 19-year-old compatriot Carlos Alcaraz overtook Nadal as favourite for the title.

The first three months of the year proved that you should underestimate 21-time major champion Nadal at your own peril, but there really are no guarantees he will even make it to Roland Garros at this rate.

Though playing second fiddle to anyone on clay is rare for Nadal, his injury woes are not. The chronic left-foot injury which saw him fall to Denis Shapovalov in Rome on Thursday has plagued him since 2005 - the same year he won his first French Open title, on his debut. It is a condition known as Mueller-Weiss Syndrome and was the reason why he missed Wimbledon, the Tokyo Olympic Games and the US Open last year, after undergoing surgery. But even with the best medical team money can buy at his disposal, this is a problem Nadal has made clear that he has no way of solving completely.

Instead Nadal, who turns 36 next month, relies on anti-inflammatories and pain relief to get him through training and playing on a daily basis. But on Thursday it was far too strong and, after the last-16 loss, he gave insight into the mental toll it was taking. “I imagine there will come a time when my head will say: ‘Enough,’” a dejected Nadal said. “Pain takes away your happiness, not only in tennis but in life. And my problem is that many days I live with too much pain.”

Even having to faintly imagine the sport without Nadal, so soon after his epic Australian Open triumph in January, feels wildly unfair. But even that win was a measure of how quickly fortunes can change, as he had spent much of the preceding autumn on crutches nursing his foot back to health.

The unpredictability of his flare-ups appears to be what frustrates him most. He could be better in a couple of days, he explained, or still debilitated by it for much longer, and it puts a huge question-mark around his ability to be ready for Paris in just eight days.

It is such a different reality to two months ago, when he was unstoppable and in the midst of his best ever start to a season. Three titles and 21 consecutive wins - including his epic five-set comeback against Daniil Medvedev in Melbourne - took him all the way through to the final of Indian Wells. Then, a rib injury scuppered his chances against Taylor Fritz, and sidelined him from the tour for seven weeks - six of which were spent without the ability to even pick up a racket.

Since returning, he has been trying to accelerate his clay preparations in Madrid and Rome, even taking to the practice court immediately after his win over John Isner on Wednesday to get more time to work on his game. "My body is like an old machine," he had joked earlier in the week. "To put this machine on again it takes some time."

Just a few days later, that light-hearted observation has become all too gravely real. The combination of time out recovering from one injury - his rib - alongside his attempts to fast-track his way back to match fitness, have antagonised the foot problem he has spent a career trying to contain.

"Even if I have a lot of experience on things, today is tough for me, no? I started the season great, then the rib happened. Since I came back, the foot has been tough, being honest... When this kind of stuff happens, the rest of the positive things disappear.

"It's time to accept the situation and fight. I have to come back. I don't know if rest, I don't know if maybe practice [will work], but I still [have] a goal in one week. I am going to keep dreaming about that goal."

Even for the man with arguably the greatest attitude in sport it has been a dispiriting week, which has tested - but not yet broken - his resolve.