'Drained and stressed' Ronnie O'Sullivan withdraws from Champion of Champions

Ronnie O'Sullivan.

Defending champion Ronnie O'Sullivan has withdrawn from snooker's Champion of Champions event on the eve of his opening match in Bolton.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