Peter Ebdon's famed mental intensity and some controversially slow play unravelled Ronnie O'Sullivan's concentration and enabled him to recover from 8-2 down to beat the odds-on defending champion 13-11 to reach the semi-finals of the Embassy World Championship.
Ebdon will this afternoon start his best-of-33-frames semi-final against Shaun Murphy, 22, who completed a 13-4 trouncing of Steve Davis.
After his victory Ebdon defended his tactics and denied he was "deliberately slowing Ronnie down. There was a lot of pressure. I didn't know what I was doing half the time. I put my heart and soul into every match."
But two former world champions condemned the extent to which Ebdon slowed the play.
"Borderline ridiculous" was Ken Doherty's verdict. "I've never seen anybody play that slow," said John Parrott. "If it had been me I'd have asked the referee if it was within the rules to play like that."
The rules preclude excessively slow play with the intention of putting off an opponent and the referee is empowered to warn a player whom he believes to be taking too long on his shot or in its selection that he risks forfeiting a frame.
Colin Brinded, the referee, made no such move, no doubt allowing for the importance of the contest and the fact that in no circumstances is Ebdon one of the circuit's greyhounds.
When O'Sullivan led 6-2 going into yesterday morning's middle session he would certainly have preferred a faster tempo than Ebdon's average shot time of 33 seconds, increased to 37 by the end of a match in which Ebdon's highest break was only 60.
Although O'Sullivan led 8-2, he found it hard graft and was indebted to Ebdon's unlucky in-off for the chance to clear with 54 to snatch the last frame before lunch to carry a 10-6 lead forward to last evening.
The match started to turn in bizarre fashion in the first frame of the new session when Ebdon, leading 22-0, took first three minutes and five seconds, then two minutes, to play shots in both of which he ultimately succeeded against unlikely odds in denying O'Sullivan a break-making opportunity.
Taking extreme care on every shot, Ebdon was leading 84-0 when O'Sullivan made a protest by playing on for an impossible number of snookers. As Ebdon continued as if each pot was costing him a pint of blood, O'Sullivan feigned sleep, asked a spectator the time and broke the skin on his forehead with a frustrated scratch.
Inexorably Ebdon accumulated the first five frames, taking the lead for the first time after a 42-minute frame. After another 30 minutes O'Sullivan missed a sitter on the penultimate red and was two down with three to play.
Ebdon threw a few lifelines after that and the champion was able to end his six-frame losing streak. The frame that proved to be the last was also nip and tuck until O'Sullivan left the frame-and-match-ball pink over a middle pocket.
Afterwards he said: "Peter's got to do what he's got to do. He's got a wife and four kids to feed, so I can't criticise him. He's there to stop me playing. That was his job. I am not out of love with snooker but mentally it's taking its toll. I'll probably have a year off. I've not made a final decision yet but I'm 90% positive."
In a final plea Ebdon said: "I'm a natural player. I play quite fast but it's a bit like a failsafe mechanism. When I'm under pressure that's how I cope. I didn't do it deliberately."