World number two Carlos Alcaraz retired from his first-round match Tuesday at the ATP Rio Open after rolling his right ankle on just the second point of the contest against Thiago Monteiro. The Spanish star took a medical timeout, had the ankle taped and won the first game but after dropping his serve in the second game he called it quits, in another setback to a so-far disappointing 2024 campaign. Shortly after the match Alcaraz told reporters the decision to withdraw was a "precaution" and that the physiotherapists who treated him had indicated the injury "is not serious." "I spoke with the physiotherapist on the court and we decided, together, that I would continue to see if it improved. It didn't, so we preferred to be careful and withdraw as a precaution," Alcaraz said, adding that he would have further tests on Wednesday.