It was clear immediately that Jannik Sinner was not himself in Cincinnati.
After a series of unforced errors and, after being down 0-5 to Carlos Alcaraz in the first set, Sinner suddenly retired from the Cincinnati Open tournament on Aug. 18, leaving Alcaraz the winner. All eyes are now on the U.S. Open, where Sinner was scheduled to compete in mixed doubles on Aug. 19, an extremely tight schedule that left some observers wondering whether he would withdraw from that too.
But why did Sinner withdraw from the Cincinnati Open? What happened to Jannik Sinner?
Jannik Sinner Said He Started Feeling Sick the Day Before the Cincinnati Open Final
Sinner gave details of his illness while speaking from the court after his retreat following the 23-minute set.
“Yesterday I didn’t feel very well. I thought I would improve overnight. It got worse. I tried to go out and play at least a short match, but I couldn’t go on. I’m very sorry for all of you,” he said in Cincinnati.
Sinner also commented on the heat, which reached past 90 degrees during the tournament.
“It’s been one of the hottest tournaments we played,” he said on court.
The world’s #1 was “battling a high fever and flu symptoms,” according to Tennis World USA. The Italian-language site Euro Sport (Sinner is from Italy) added another detail, writing that Sinner started play in Cincinnati “with a temperature of around 38 degrees Celsius.” In Fahrenheit, that’s a temperature of 100.4 degrees. That’s generally considered a sign of a fever.
Jannik Sinner Said the U.S. Open Is Going to Require a ‘Couple of Days of Recovery’
The ATP Tour then released quotes from Sinner in which he spoke about the U.S. Open.
“I love Grand Slams a lot. This is the main, main tournaments for my season and for my career,” Sinner said.
“So US Open is going to be tough tournament, but in the same time, I’m looking forward to it. If I’m ready, physically and mentally, I will be ready to push,” he added. “So as I said, now a couple of days of recovery, and then we get again back to work, and hopefully we’ll be ready. So for sure, the main goal here in the US.”
He added that he “now [has] a couple of days of recovery,” which would seem to cast his mixed doubles debut in doubt.
Carlos Alcaraz Offered Jannik Sinner Support After the Italian Withdrew
Alcaraz responded to Sinner’s withdrawal by consoling him with a pat on his shoulders.
Heartbreaking 💔
Get better soon, @janniksin 🙏 pic.twitter.com/KMGSxJpEwG
— Tennis TV (@TennisTV) August 18, 2025
Sinner’s withdrawal matters for several reasons. It mattered to fans and spectators who were looking forward to the continuation of men’s tennis’s top current rivalry, which was cemented with their epic, and now classic, French Open match. Alcaraz won that, but Sinner took Wimbledon, so all eyes were on Cincinnati.
The withdrawal also matters because it makes Alcaraz’s path to take the #1 ranking from Sinner easier. And it raised questions about Sinner’s strength going into the higher-prized U.S. Open. It comes on the heels of Sinner’s doping scandal.
It’s not the first time that Sinner has been sick before a tennis match. In 2024, he wrote on X, “This is not an easy announcement to make. My team and I arrived early to prepare as best as possible, but unfortunately, I started feeling unwell during training and saw the doctor on Sunday. It turns out I’ve come down with a virus. I’m feeling better now, but I’m still not ready to compete here in Paris. I was really looking forward to this tournament, so it’s disappointing, to say the least. For now, I’m focusing on recovery and getting back to 100%. I’ll be aiming to come back stronger for Turin!”
Related: Jannik Sinner, Carlos Alcaraz Rivalry: How Cincinnati Open Win Could Affect No. 1 Ranking
Related: Jannik Sinner Doping Scandal Explained After Steroids Test
