Ronnie O'Sullivan did not mince his words as he admitted to feeling 'horrible' despite thrashing Pang Junxu to reach the quarter-finals of the World Snooker Championship. The man from Essex cruised to a 13-4 victory over his Chinese rival, setting up a last-eight showdown with Si Jiahui. The Rocket only needed one frame in Monday's evening session to wrap up the match.

He fell just short of a century break, missing the green on 95, but did more than enough to claim victory and maintain his hopes of an eighth Crucible triumph. Despite playing well, O'Sullivan was furious with his own performance and made no attempt to hide his true feelings. Speaking to BBC Sport afterwards, he admitted to lacking confidence in his own game despite chopping and changing his cues in search of the perfect match.

"I feel so unconfident," said O'Sullivan. "It's horrible, even when I'm playing alright. In the balls, I was alright tonight, but there are so many different parts of the game you've got to get right. It's hell.

"It's not even about winning, it's about going there and being confident enough to just do yourself justice. It's nice to win but you just want to be part of a good game.

"I've always felt better if I've played well in a game and lost than played terrible and won. I know I'm probably not normal so I've accepted that.

"I love grafting but I just can't handle not knowing where the ball is going. I couldn't even tell you if it was a good cue because I'm hitting the ball that badly.

"I've gone through about 30 cues and I've got to the point where I can't really judge. The way I'm hitting the ball, they all sound terrible so I can't even tell if it's a good cue or not."

In spite of his concerns, O'Sullivan refused to write off his chances of securing Crucible glory having battled through similar issues in the past.

"I've won this tournament many times before while playing what I consider bad, so it can be done," he said. "When you're in your early forties and late thirties, it's probably much more achievable.

"When you're nearly 50 and you struggle to bend down and do your shoelaces up, it gets a bit hard. People say: 'You're not as bad as you think', so it's really hard to judge. Feeling-wise, it's probably the worst I've ever felt, to be honest with you.

"I don't even know where my back arm is, where my left leg is. Sometimes I can't even see where I'm hitting and I'll butcher a shot. It's difficult, it really is difficult."