Britain’s Jack Draper was forced to retire in the third set of his Mexican Open semi-final in Acapulco.
The 22-year-old had treatment from the physiotherapist and tournament doctor in the second set against Australian defending champion Alex de Minaur.
De Minaur had taken the opening set 6-3 before the British number three came back to win the second 6-2 thanks to some strong returns.
Draper was trailing 4-0 in the decider when he withdrew from the match.
The Australian world number nine wished Draper “a speedy recovery”.
De Minaur added: “Even though I dropped that second set, I knew he was hurting from then and I just told myself to bring up the intensity, try and get a head start in the third set and make it a little bit harder for him.
“He’s a hell of a player, a hell of a talent and I hope it’s nothing too serious.”
De Minaur will play Norwegian Casper Ruud in the final after he defeated Denmark’s Holger Rune 3-6 6-3 6-4.