World number one Ronnie O'Sullivan came from behind to beat qualifier Ryan Day 13-10 late on Monday and complete the World Championship quarter-final line-up.

O'Sullivan trailed 9-7 at the start of the final session but took advantage of some costly errors from Day to win six out of seven frames and seal victory.

"It was a tough game and I'm lucky to be through," O'Sullivan said at the post-match news conference.

"He had his chances to win, but he wasn't able to finish me off."

Briton O'Sullivan, a twice winner, is now looking forward to a last eight clash with another twice former champion, Mark Williams.

"I need to raise my game a little because he's playing well again," O'Sullivan said.

Latest results QFs (best of 25):
Doherty leads Fu 7-6; Ebdon leads Murphy 7-1; Dott leads Robertson 9-4; O'Sullivan level with Williams 4-4.

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