Jannik Sinner pulled out of the US Open mixed doubles tournament shortly before it began on Tuesday, a day after he quit in the first set of the Cincinnati Open final because he was feeling ill.

World No.1-ranked Sinner, the defending champion in singles at Flushing Meadows, was supposed to compete in the mixed doubles event with Katerina Siniakova.

Sinner retired from the Cincinnati title clash while losing 0-5 to Carlos Alcaraz on Monday. He admitted that he came into the match feeling poorly, but still tried to put up a fight. “I was not feeling great. I tried to push through, but I couldn’t handle it,” said Sinner.