Qualifier Ian McCulloch grabbed a 6-2 lead over Welsh sixth seed Matthew Stevens as their World Snooker Championship semi-final got underway at the Crucible Theatre here on Thursday. McCulloch, a 100-1 outsider at the start of the tournament, compiled three half-centuries and a 127 clearance to rattle the Welshman in the best-of-33-frames showdown. In the other semi-final, 2002 winner Peter Ebdon, who put out defending champion Ronnie O'Sullivan in the quarter-finals, also leads Shaun Murphy 6-2 after their first session.
McCulloch had already showed his cool approach in triumphing in last-frame deciders with 2004 runner-up Graeme Dott and two-times world champion Mark Williams earlier in the tournament.
He had secured his place in snooker's elite top 16 for the first time as a result of his quarter-final success over Alan McManus.
And the 33-year-old made an impressive start and capitalised after Stevens missed a yellow when playing left-handed with a decisive run of 61 to take the opening frame.
McCulloch punished Stevens for a poor break-off shot in the next with a break of 53 and missing a regulation black off its spot did not prove costly as he doubled his lead.
Stevens, in his fifth world semi-final in the last six years, found himself trailing 3-0 after underhitting a blue - and in nipped McCulloch for another half-century.
McCulloch then completed a pre-interval whitewash, edging a thin red into the middle pocket on his way to a 127 clearance.
Stevens won the fifth to get on the board before McCulloch fought back with another ton. Again the lead was once reduced, but the Preston star showed his fighting spirit again to win the last frame of the day.
SEMI-FINALS (BEST OF 33 FRAMES): Peter Ebdon (ENG x8) leads Shaun Murphy (ENG) 6-2.
FRAME SCORES (EBDON FIRST): 78-10, 22-93, 101-9, 77-22, 0-77, 76-20, 79-8, 99-40.
Ian McCulloch (ENG) leads Matthew Stevens (WAL x6) 6-2.
FRAME SCORES (STEVENS FIRST): 38-72, 39-66, 23-61, 4-127 (break 127), 53-43 6-122 (122), 71-4, 0-83.