Carlos Alcaraz won the Cincinnati Open title in a little over 20 minutes Monday afternoon, after his nearest rival and world No. 1 Jannik Sinner retired through illness down 5-0. Sinner fought back tears as he was forced to quit the match, which was poised to be another instalment in the most compelling current rivalry in tennis.

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."