The Spaniard will not defend his title at the tournament that starts on August 13 because of "an ongoing wrist injury."

"We know Carlos is doing everything he can to get back to playing tournaments as soon as possible," tournament director Bob Moran said in a statement. "We wish him the best with his recovery and look forward to welcoming him back to Cincinnati in the future."

The move will spark concerns over Alcaraz's upcoming title defense at the US Open, the final Grand Slam of the year, which starts on August 30 in New York.

The elite hard court tournament in Cincy is the last major tune-up for the Open.

The 23-year-old Alcaraz has already opted out of the French Open and Wimbledon this year as he recovers from the injury suffered in the first round of the Barcelona Open in April.

The seven-time Grand Slam champion pulled out of tournaments in Madrid and Rome before withdrawing from Roland Garros in a move he said he and his team had decided was "the most prudent thing to do."

He then missed Wimbledon, where his rival Jannik Sinner prevailed for the second year in a row, this time against Germany's French Open winner Alexander Zverev.

In opting out of Wimbledon, Alcaraz said his recovery was going well but that he was still not ready to play.

It marked the third Grand Slam that Alcaraz has missed since he made his main draw debut at the 2021 Australian Open.

He became the youngest man to complete the career Grand Slam in January with his triumph at the Australian Open. He also won the ATP title in Doha in February.