US OPEN champion Jannik Sinner has provided a scare before next week’s tournament after he retired from the Cincinnati Open final against Carlos Alcaraz.

Sinner was only on court for 24 minutes, but was out of sorts in hot conditions in Ohio and broken three times by rival Alcaraz to trail 5-0.

With Alcaraz about to serve for the set, four-time grand slam champion Sinner called for the trainer and decided to quit to hand the world number two a maiden Cincinnati Open title and cast doubt over his involvement at Flushing Meadows, where the action gets under way on August 24.

Sinner addressed the crowd after his retirement, saying: “I’m super, super sorry to disappoint you.

“From yesterday I didn’t feel great, I thought I would improve during the night, but it came up worse. I tried to come out and make it at least a small match but I couldn’t handle more. I’m very, very sorry for all of you.”

After titanic tussles at Roland Garros and Wimbledon in recent months, another thrilling instalment was predicted at this ATP 1000 event.

Sinner had not dropped a set on his way to the final, but that changed after game one as Alcaraz surprisingly clinched a break to love.

Alcaraz held to move 2-0 up although only after being taken to deuce and yet it was not a sign of things to come.

More struggles on serve followed for Sinner, who saved two break points but suddenly was three down and called for an ice bag during the break.

It failed to stem the tide as the Italian was immediately forced to rush around court to keep up with Alcaraz.

When Sinner barely moved to get to a drop shot in the fifth game, the writing was on the wall and after a double fault made it 5-0, Alcaraz watched his adversary call for a trainer and bring the final to a premature end.

Alcaraz proceeded to write “sorry Jannik” on the camera before he briefly consoled the world number one.

“Well, yeah it is not the way I want to win matches, to win trophies and I have to say sorry. I can’t understand how he feels right now,” Alcaraz said.

“I said many, many times you are a true champion and I am pretty sure from this situation you will come back better and stronger like you always do.”