Jannik Sinner retired with an apparent illness 23 minutes into the first set of the Cincinnati Open final against Carlos Alcaraz.

Carlos Alcaraz won the Cincinnati Open on Monday after Jannik Sinner was forced to retire due to illness. Alcaraz was already up big on Sinner, the World No. 1, when he had to retire. Sinner told the crowd that he hoped to play after feeling bad overnight, but he couldn't make it work.

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.