World No. 6 Marin Cilic announced on Friday that he has been forced to withdraw from the Western & Southern Open in Cincinnati, where he is the defending champion, due to an abductor injury.

"I was really eager to play in Cincinnati, where I won my first-career ATP World Tour Masters 1000 singles title last year and where I’ve had some of the best performances during my career, but I still don't feel at 100 per cent to compete at the top level and to defend my title there," said Cilic.

“I had already started with my preparation and the progress is going well, but there isn't enough time for me to prepare for Cincinnati and to be completely ready to play there. I feel very confident that I will be back in action very soon."

The 28-year-old Cilic suffered the injury last month at Wimbledon, where he lost to Roger Federer in the final on 16 July.