McManus rode his luck to beat Lee

Four top-16 stars had already crashed out at the second-round stage before McManus produced a surprise 5-4 victory in the first game of round three.

Lee led 4-3 with McManus needing snookers when disaster struck for the "devastated" title holder.

Attempting to sink the final yellow, Lee missed his pot and watched in disbelief as the cue ball found its way into a pocket instead.

McManus won the frame on the black and then produced a superb 51 clearance in the decider after Lee missed a pink into a middle pocket.

"I don't remember the last time I lost to Alan but if you are not firing on all cylinders that's what happens," said Lee.

"I don't think Alan played that well either but I couldn't get over the line.

Stephen probably thought he'd won the match three or four times but the final ball wouldn't go in for him Alan McManus

"I felt good at 4-3 but nothing seemed to happen. That was a one-in-10 chance the white going in, but even then he didn't clear up from there.

"To be honest, I'm disgusted with myself. I'm going to take three weeks off and then come back for the British Open."

McManus said: "I'm delighted to be through. Stephen probably thought he'd won the match three or four times but the final ball wouldn't go in for him."

He now plays Nigel Bond or David Gray for a place in the last four.

Qualifier Jimmy Michie's fourth win of the event took him to the brink of his first ranking tournament quarter-final since April 1999.

The Yorkshireman upset world number 11 Mark King 5-2.

Welshman Matthew Stevens, the world number eight, again flattered to deceive. Despite his talent, Stevens won only one frame against Gray.

If things are getting a bit tough I just think Barry [McNamee] would love to be here and that puts things into perspective Patrick Wallace

The Londoner will now play stable mate Bond, a 5-3 winner over world number 16 Joe Swail.

Gerard Greene, the world number 63, rounded off Wednesday's upsets when he edged out former British Open champion Fergal O'Brien 5-4.

Greene has now won more matches in the LG Cup - five - than he managed in the whole of last season.

Earlier in the day, Patrick Wallace dedicated his 5-3 victory over former world number one Ken Doherty to Barry McNamee, who was killed earlier this year.

The world number 36 used to practice with former Northern Ireland amateur champion McNamee and he is organising a tournament in his friend's memory.

"Players like Ken, Fergal O'Brien, Joe Swail and Michael Judge have said they will play," said Wallace.

"I really miss Barry. He was a good friend and someone I practised with on a regular basis.

"I have been thinking about him when I'm playing my matches.

"If things are getting a bit tough I just think Barry would love to be here and that puts things into perspective."