Rank outsider Graeme Dott made a mockery of the bookmakers odds to open up a 5-3 lead over Matthew Stevens in his first Embassy World Snooker Championship semi-final at the Crucible Theatre.

Dott showed few nerves in the best-of-33 frames marathon against Stevens, who was made overwhelming favourite at 4-1 on by Ladbrokes to book a final showdown against either Ronnie O'Sullivan or Stephen Hendry.

The stakes could not be higher for 26-year-old Dott, who needed to overcome his Welsh opponent to retain his place in snooker's elite top 16 for the 2004-2005 campaign after provisionally sliding from 13th to 26th spot ahead of the tournament.

Devout Rangers fan Dott had a disastrous first half of the current season and smashed his cue in frustration when he stopped at a motorway service station in January.

But the Scot showed that Stevens, bidding to reach his second world final, would have no stroll to victory.

The opening frame was a scrappy affair spanning 35 minutes with both players taking time to settle after the switch to a one-table arena.

Stevens, competing in his fourth world semi-final in the last five years, edged into a 42-27 lead but he missed the final yellow down the rail and Dott cleared the colours.

The second was more clear-cut with a half century giving Dott the early initiative and then Stevens seeing a red double back over the black pocket after he had tried to play safe.

Dott needed no second invitation and a clearance of 76 clinched matters with Stevens failing to pot a ball in the process.

Stevens had declared himself as "fresh as a daisy" going into the match after his series of first-round exits following his UK Championship triumph in December.

And he finally found some fluency in the third as runs of 40 and 36 enabled him to open his account as Dott conceded.

But Dott, who is guaranteed £63,200 by reaching the last four - the biggest pay day of his career - restored his two-frame advantage before the interval. His opening run of 61 proved decisive.

Dott had a golden chance to move 4-1 ahead in the next but after compiling 55 he missed a simple black off its spot and Stevens took full advantage with a 43 clearance to the pink.

The sixth frame was a cat-and-mouse affair lasting nearly 43 minutes after Dott had opened with a run of 43.

Stevens ate into the lead but eventually conceded after failing to escape from a series of snookers on the yellow.

He retaliated in the best possible manner with a 115 clearance - his sixth century in this year's championship to reduce Dott's lead to 4-3.

Dott was first amongst the balls in the final frame of the session with a 44 and then looked favourite when he came back to the table.

He missed a straightforward red to leave all the balls at Stevens' mercy but after reaching 31 he was clearly unhappy at a small patch on the table occupied by the cue ball.

Referee Jan Verhaas tried to smooth down the troublesome area but then Stevens missed the pink into the middle and was left shaking his head as he walked back to his chair.

Dott accumulated enough points to leave Stevens requiring snookers and he finally conceded after another long drawn-out affair lasting nearly 40 minutes.