Carlos Alcaraz was tipped to win the second Grand Slam of his career in Paris (Picture: Getty)

Carlos Alcaraz admits the stress of playing Novak Djokovic in the French Open semi-finals was the reason behind his huge struggles with cramp on Friday.

The Spanish world No.1 was suddenly unable to move and required treatment in the third set of the match against the 22-time Grand Slam winner.

Alcaraz was seen shaking his head at his box and looked on the verge of retirement but carried on as Djokovic eased to victory to set up a final against Casper Ruud on Sunday.

It was a surprise turn in the match after Alcaraz impressively won the second set and the 20-year-old has now opened up about why he was cramping so badly.

‘It is not easy to play against Novak, he is a legend of our sport,’ Alcaraz said. ‘It has been really tough for me. I have never felt tension like I did in that match.

‘If someone says he goes onto the court with no nerves playing against Novak, he lies.

‘The tension of the match was why the cramping happened. I started the match really nervous.

‘I would say the first set and the second set was really, really intense and I started to cramp in my arm.

‘At the beginning of the third set I started to cramp every part of my body, not only the legs. The arms, as well, every part of the legs.

‘It was really tough for me to move at the third set, and in the fourth set let’s say I had a little chance, but it was really tough. My full body started to cramp.

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‘I would have felt sorry about myself if I retired. I’m in a semi-final of a Grand Slam. If I retired from that, it could have been really tough for me.

‘Thinking about the fourth set, I thought that probably I have 1% chance to come back.

‘In the fourth set I had break points in the first game and after that, I just continued playing. I was not thinking about retirement.’

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‘I have never felt tension like I did…’