Underdog Graeme Dott is still on course for a place in his first Embassy World Championship final after maintaining a two-frame lead over Matthew Stevens at the half-way stage of their best of 33 semi-final clash.
Dott will head into this evening's third of four sessions holding a 9-7 advantage after sharing the eight frames in the morning battle.
And the Scot also had the distinction of registering the 50th century of this year's championships with a 117 in frame 11 giving him his first ton of the 2004 finals.
Stevens, who had began the match on Wednesday at 1-4 on to go through to the final, was still below his best and will be relieved to have such a narrow deficit to overcome.
He is still favourite but his odds have been lengthened to 5-1 and he is finding it hard to break down the resistance of the determined Dott, who was on the verge of quitting the game last summer.
The opening frame was strewn with errors from both players before Stevens eventually halved his deficit.
Dott escaped from three snookers but left an easy final red from which the Welshman went onto compile sufficient points.
The next frame was far more clear-cut with a run of 84 from Stevens putting the 2000 world runner-up back on level terms at 5-5.
But Dott, needing to reach the final to maintain his place in the top 16 for next season, was unfazed and his reply was impressive as a clearance of 117 to the pink brought up the 50th century of the 2004 championships.
He held his nerve in the next after Stevens had broken down on 54 to pinch the frame with a half-century to the pink.
Dott made it three frames in a row with two runs of 32 and then looked set to secure number 14 after he came from 62-22 behind.
He cleared the final two reds and the colours to the pink but left a difficult cut on the black and let it hanging over the pocket.
Dott was visibly gasping with disbelief that the black did not drop and put him 9-5 ahead as a grateful Stevens seized his reprieve.
Stevens was still not firing on all cylinders but a 51 in frame 15 ultimately proved decisive, although the frame still lasted nearly half an hour before Dott conceded.
But an opening 33 helped Dott regain his two-frame cushion and leave Stevens with plenty of food for thought.
Firm favourite Ronnie Sullivan will be looking to increase his grip on the other semi-final when he resumes on Friday afternoon holding a 6-2 advantage over seven times champion Stephen Hendry.
The Rocket dominated the opening session as he bids to achieve his first-ever win over Hendry in Sheffield at the fourth attempt.
O'Sullivan put together breaks of 85, 127, 67 and 98 and won five frames in a row at one stage before Hendry, 9-2 to take the title, added to his 61 in frame two with an 81 in the last of the session.