Defending champion Ronnie O'Sullivan has withdrawn from snooker's Champion of Champions event on the eve of his opening match in Bolton.

O'Sullivan had been scheduled to play Zhang Anda in group one on Wednesday, with the winner facing either John Higgins or Chris Wakelin for a place in the semi-finals.

The seven-time world champion, who lost to Zhang in the semi-finals of the International Championship in Tianjin on Saturday, has been replaced in the field by Ding Junhui.

O'Sullivan wrote on X, former known as Twitter: "Hi guys, just wanted to let you know I'm unfortunately withdrawing from the Champions of champions event tomorrow.

"Mentally I feel a bit drained and stressed and I want to look after my mental health and my body. I'm sorry to all the fans but I'll be back stronger."

O'Sullivan is expected to return to action in the UK Championship in York later this month.