
Frances Tiafoe, a finalist at last year's Cincinnati Open, was forced to retire from his Round of 16 match vs. Holger Rune during the second set on Wednesday because of injury. An official injury diagnosis hasn't been shared, but the Tennis TV broadcast said that Tiafoe's "back locked up" and he wasn't able to recover to finish out the match.
The American tennis star hasn't shown any signs of injury in tournaments leading up to the Cincinnati Open, so it's unclear how he injured himself.