Sheffield (Agencies): Four-time world champion Mark Selby maintained a slender one-frame lead over Mark Allen after the third session of their World Championship semi-final.
Selby resumed with a 7-6 overnight advantage and pulled further clear with breaks of 63 and 112 as he won the first two frames on Saturday.
However, a pumped-up Allen responded with runs of 58 and 92 as he won four of the next six to trail 11-10.
Their best-of-33 match will be played to a conclusion from 19:00 BST.
The winner will face either Luca Brecel or Si Jiahui in the best-of-35 final which begins on Sunday at 13:00.
While Chinese debutant Si leads his Belgian opponent 14-10 in a free-flowing encounter that has been brimming with audacious potting and attacking snooker, Selby and Allen’s contest has been the opposite.
A number of lengthy tactical exchanges have featured throughout a fiercely contested affair between players ranked second and third in the world.
The duo, who have won five ranking titles between them this season, broke the mould in the first two frames of the morning with Selby finding some fluency among the balls to open with a half-century and then compose his second century of the match.
However, with a vociferous Crucible crowd firmly behind Allen, the Northern Irishman then won the third-longest frame of the match lasting nearly 44 minutes to reduce his deficit to two frames.
Selby restored his three-frame lead with a carefully crafted 53 heading into the mid-session interval, but then missed a green in a hard-fought 18th frame which Allen won.
A dramatic 19th frame saw the Englishman break down on 30 after missing a red to the left corner and Allen go in off the blue to allow Selby an opportunity to take the frame to a respotted black.
But he ran out of position on the blue and wafted it over the bottom-corner pocket allowing the nine-time ranking-event winner to claw another frame back.
The pair then traded the final two frames of the session to leave the prospect of another epic late-night finish at the Crucible.
