The world's top two tennis players met again in the Cincinnati Open this week with No. 1 Jannik Sinner facing No. 2 Carlos Alcaraz in their fourth finals matchup of 2025.

The latest chapter of the Jannik Sinner-Carlos Alcaraz rivalry took a stunning turn on Monday when world No. 1 Sinner retired in the first set of the Cincinnati Open final due to an unspecified health issue.

Sinner retired with apparent illness in the first set of Monday's Cincinnati Open final against Alcaraz after digging a 5-0 deficit. Sinner remained on the court for the trophy ceremony and addressed his condition while speaking with the crowd. He didn't offer specifics, but said that he "didn't feel great."