Elena Rybakina's bid to overtake Aryna Sabalenka as world number one ended abruptly when she retired with a left ankle injury during her Cincinnati Open quarter-final against Iga Swiatek. The Kazakh second seed needed to reach the final to claim the top ranking after Sabalenka's surprise loss to Sara Bejlek, but managed only five games before quitting at 4-1 down.

Rybakina called for a medical timeout at 40-40, played one more point, then withdrew. "It's painful to walk. We'll know more tomorrow when we have the MRI," she said. Swiatek, who beat Rybakina in last week's Canadian Open final, advances to face Jessica Pegula in the semi-finals, aiming to defend her Cincinnati title.

In the men's draw, Flavio Cobolli staged a 2-6 6-3 6-4 comeback over Tommy Paul after requesting M&M's during a changeover for energy. The Italian will face Arthur Fils, who dispatched Thiago Agustin Tirante in 64 minutes without facing a break point, becoming the first Frenchman since Guy Forget in 1991 to reach three Masters 1000 semi-finals in a season.