Rafael Nadal was told he could no longer play tennis in his teens, he says, as he was forced to train sitting on a chair.
Nadal turned pro just 15-years-old and claimed the first of his 13 French Open titles just four years later.
It was after that match though when he was given some devastating news.
"At nineteen, after I had just won my first Roland Garros, they told me that I would no longer be able to play due to a deformity in my left foot.” Nadal told Corriere Della Sera.
“The pain was so great that I trained to hit the ball sitting on a chair in the middle of the court.
"Then I recovered, thanks to an insole that changed the position of the foot, but inflamed my knees."
Nadal attributes being able to fight through those tough times to the same thing that has got him through other rough periods in his career - his mental strength.
“[You do it] with a positive mentality, by transforming the fragility of the body into moral strength.
"Sooner or later things will fall into place. We must equip ourselves to resist, because there is no other solution than to resist.”
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