Gael Monfils has pulled out of the Western and Southern Open, meaning Dominic Thiem is safely into the quarter-finals.
Ninth seed Monfils defeated Pablo Carreno Busta and Marcos Baghdatis en route to the third round, but will play no further part after it was confirmed he had sustained a back problem.
"No.9 seed Monfils has withdrawn from the tournament citing back injury. Wishing him a speedy recovery! #CincyTennis," read a tweet from the tournament's official account.
World number nine Thiem, seeded eighth for the ATP 1000 event in Cincinnati, is subsequently the first man into the last eight, where he will meet either fourth seed Milos Raonic or Yuichi Sugita.