Jannik Sinner has pulled out of the new-look US Open mixed doubles due to illness.
The world No1 retired from his Cincinnati Open final against Carlos Alcaraz when 5-0 in the first set on Monday.
Sinner had been due to fly straight to New York, New York to team up with Katerina Siniakova on Tuesday. They were set to face Alexander Zverev and Belinda Bencic.
However, the 24-year-old has not recovered in time and the American duo of Danielle Collins and Christian Harrison will take their place in the draw instead.
Speaking after he brought a premature end to his match with Alcaraz, Sinner revealed that he had fallen ill on Sunday and felt worse in the build-up to the final.
"I'm super sorry to disappoint you," Sinner said to the fans.
"From yesterday I didn't feel great, I thought I would improve but it came up worse. I tried to come out, to make it at least a small match, but I couldn't handle more.
"I am very sorry for all of you. I know that maybe some of you, on a Monday, you had to work or do something else, so I'm really sorry."
Sinner's withdrawal from the US Open mixed doubles is a blow to organisers.
The two-day event is taking place ahead of the Grand Slam for the first time in an attempt to increase the number of big-name singles players involved.
Best-of-three matches will be played, with only four games needed to win a set. There will be no advantage, with the winner of a deuce point taking the game, and 10-point match tie-breaks instead of a third set.
Emma Raducanu has teamed up with Carlos Alcaraz, while Jack Draper is the number one seed alongside Jessica Pegula.
Those two pairings face each other in the round of 16 on Tuesday night, which you can follow on Standard Sport’s live blog.
