Spain’s Alcaraz, who can return to number one in the world with a third ATP Masters 1000 title this week, led 6-2, 2-0 when Draper, who had been treated by a physio, called a halt after 46 minutes on court.

“This is not the way anybody wants to win a match, because something is wrong,” Alcaraz said. “All I can say is I hope to see him get well soon.”

Alcaraz, 19, became the youngest men’s world number one ever last year after his precocious US Open triumph.

But after an abdominal injury hindered him late last year and a leg injury forced him to miss the Australian Open he has slipped behind Serbian superstar Novak Djokovic.

Djokovic is absent this week as he is prohibited from entering the United States because he declined to be vaccinated against Covid-19.

Alcaraz returned to action last month with a victory in Buenos Aires and a runner-up finish in Rio de Janeiro – where he suffered a strained hamstring that prompted him to pull out of Acapulco.

He’s looked in fine form in Indian Wells, although Draper couldn’t offer much resistance.

It was a disappointing finish to the week for Draper, who beat childhood hero Andy Murry in the third round.