Anthony Hamilton reached the Embassy World Championship quarter-finals for the third time in five years after battling past Joe Swail at the Crucible on Saturday.

Hamilton, ranked 20th in the world, won five of the final session's eight frames to beat Northern Ireland's top player 13-11 and secure a last eight meeting with Ronnie O'Sullivan.

The Nottingham potter, beaten 13-3 by John Higgins in the 2000 quarter-finals and 13-6 by Peter Ebdon at the same stage in 2002, resumed trailing 5-3 after the first session.

Swail, a Crucible semi-finalist in 2000 and 2001, extended his advantage to 7-4 but Hamilton recovered to be level at 8-8 going into the final session.

And Hamilton moved ahead for the first time with a run of 54 to make it 9-8 before edging into the lead at 10-9 and 11-10.

Swail's 69 enabled him to draw level at 11-11 but he missed a pink on 30 in the next and Hamilton stepped in with an 86 clearance.

The 32-year-old, who knocked out Crucible legend Steve Davis in the first round, then made a break of 61 in the 24th frame before clinching victory when Swail left the last red out of a snooker.

Hamilton said: "I couldn't believe it was 8-8 going into the final session because I could have lost the first 7-1 and the second 6-2. It's the best result I've ever had in a match.

"I didn't think I stood any chance of winning until I led 9-8 and then I was more focussed and more relaxed."

Hamilton has practised with unpredictable O'Sullivan at Ilford, although the pair have not crossed cues since before Christmas.

He said: "I need to get on the practice table and work on my game. If I sort out a few fundamental things I'll be a different player.

"To beat Ronnie I'll have to score heavily and take my chances. Good scoring is hard to top, even if Ronnie is playing out of his skin."

Swail admitted he had been disappointed to be held to 8-8 after the first two sessions.

He said: "I dominated both those sessions but couldn't get away from him. Coming into tonight I knew he would have to start playing and that while he could only get better, I could only get worse.

"When I got to the semi-finals before I felt I wasn't ready because I wasn't scoring heavily enough but I genuinely thought I could win it this year because I'm scoring better than ever."