World number two Carlos Alcaraz is to have tests on his ankle after sustaining an injury that forced him to retire from his Rio Open first-round match against Thiago Monteiro on Tuesday. The reigning Wimbledon champion needed medical attention after twisting his right ankle on the second point of the contest. He returned to the court a little later with heavy strapping and broke Monteiro’s serve, but after dropping his own in the next game, he decided to call it quits.

The Spaniard hasn’t won an ATP title since beating Novak Djokovic to win the Wimbledon trophy last July. He had a troubled start to 2024, slumping to a four-set defeat by Alexander Zverev in the Australian Open quarterfinals and losing in the semi-finals of the Buenos Aires tournament to 21st-ranked Chilean Nicolas Jarry last Saturday.

The setback won’t help the Spaniard in his battle to retain his No. 2 ranking from surging Italian Jannik Sinner, who leads him by just 535 points after winning the Rotterdam Open on Sunday. Sinner can close the gap to 1,000 points when he defends his Indian Wells title next month.

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Alcaraz’s withdrawal meant that Brazil’s Monteiro will now take on compatriot Felipe Meligeni Alves in the second round for a place in the quarterfinals, with the winner facing another home player in the shape of Pedro Cachin. The pair had met in qualifying, and both made it to the main draw with straight-set victories.

After a slow start to the year, Alcaraz hoped to improve on a run to the quarterfinals at the French Open in May, where he will play Djokovic and Rafael Nadal again for a place in the final. He was unbeaten in his previous eight matches on clay before the defeat to Zverev.

Alcaraz is expected to recover for the BNP Paribas Open in Indian Wells, which begins on March 10, and the Miami Open in April. The Spaniard also has the Queen’s Club and Wimbledon on his schedule this summer, where he is the defending champion.

“I just wish him a speedy recovery, that it’s nothing serious or that it won’t affect his season,” said the 29-year-old left-hander, who improved to 2-0 against Alcaraz with victory in their only previous meeting at the Melbourne-1 event in 2021.

Alcaraz has a strong record at the French Open, winning in 2022 and finishing runner-up to Cameron Norrie last year. He is the only non-Djokovic or Nadal player to have won at Roland Garros in the last three years, but he hopes for a better outcome this time.