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.

After his 6-4, 6-3 victory against Alexander Zverev, Carlos Alcaraz set up a final showdown with Jannik Sinner, a rematch of the Rome, Roland Garros and Wimbledon title matches this season.

Ten seeded players were in action during the Cincinnati Open quarterfinals Aug. 15. Here's how the action unfolded in Mason.