Ronnie O'Sullivan recovered from a 9-6 deficit to beat Barry Hawkins 10-9 and set up a Tour Championship final date with Neil Robertson.
The two men were tied up all square after a topsy-turvy afternoon session, during which O'Sullivan slipped into a 3-0 lead, lead 4-3, then end up level.
O'Sullivan began the evening session by nudging himself into a 5-4 lead, eventually winning the ninth frame after errors from both men, with the fatal one coming when Hawkins missed a difficult red while using the rest.
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But that did not deter Hawkins, who was full of confidence after defeating Judd Trump in the quarter-finals, and he responded with breaks of 74, 50 and 103 to turn the one-frame deficit into a lead.
O'Sullivan arrested the momentum against him with an excellent 78 to cut the arrears to one, a break which was only curtailed by the cue ball running into the pocket after a customary pot.
Hawkins outwitted O'Sullivan in a lengthy safety battle to make a frame-winning 56 in the 14th to restore his two-cushion advantage.
And suddenly, with a superb long red straight from O'Sullivan's break off, he was one frame away from victory after another well-made 73.
Hawkins looked good for the match when he got into his work with a 46, but a missed red to the corner pocket gave O'Sullivan a lifeline he scarcely expected, which he took with a fantastic 71, despite the black being tied up and many of the remaining reds sitting on cushions.
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After punishing a poor break off from the world champion, Hawkins missed a black and set O'Sullivan up. The Rocket responded with an error of his own, only for another miss to dent Hawkins' hopes. A second invitation was all O'Sullivan needed to rattle off another frame with a brisk 90 and get his comeback in motion.
O'Sullivan drew level by triumphing in a tense 18th frame which saw both men squander chances to win. Eventually, the fifth seed capitalised on a missed green to seal it and take the match into a decider which had looked nigh-on impossible just 40 minutes earlier.
The tension continued into the 19th frame as both players missed chances to make big breaks, with O'Sullivan squandering a routine red which would have all but wrapped up the match.
Hawkins returned to the table needing a snooker, but a double kiss left O'Sullivan with a simple pot on the yellow. He could not follow it up with the green but Hawkins conceded and was left to rue a golden opportunity let slip.
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