Ronnie O'Sullivan survived an almighty scare to beat Jimmy White 4-3 and keep his hopes of a successful title defence alive at the Champion of Champions.
O'Sullivan trailed the six-time world championship runner-up 3-0 before rattling in four successive frames to win the match - then turned on the style against John Higgins to reach the last four.
The 'Rocket' was pushed to the brink by White, who missed a series of strong opportunities to roll back years and clinch a famous victory in their group stage match.
But after Higgins saw off Stuart Bingham in the second match of the afternoon session, O'Sullivan returned to action and produced a superb performance to sink the Scot 6-3.
A break of 104 nudged him ahead for the first time in the match at 2-1, and a quick-fire run of 77 helped him re-establish his advantage at 3-2.
A missed green helped Higgins haul back level but O'Sullivan was playing like he had no time to waste and promptly reeled off three frames in a row to set up a meeting with Neil Robertson.
Earlier in the day, trailing 3-0 having been careless himself, but faced also with a White performance which rolled back the years and then some, O'Sullivan appeared set to be on the receiving end of one of the biggest upsets of the year.
But White, who had chances in frames five, six, and seven, was unable to haul himself over the line as O'Sullivan forced his way through following a series of reprieves.
Even the final frame looked set to go White's way as he opened the balls and a lead, but a poor missed red confirmed that the tide had turned and allowed O'Sullivan to mercilessly swoop in.
O'Sullivan had been way below his best throughout the match, but he sparked into life with a run of 74 in the fourth frame, before taking the following two thanks largely to his opponent's generosity.
When his chance finally came in the decider, O'Sullivan never looked like returning the favour, a quickfire 76 finally earning him a place in tonight's Group 1 decider against John Higgins, who beat Stuart Bingham comfortably enough 4-2.
White started the match in electric form, and threatened a maximum break with seven reds and seven blacks in the opening frame before running out of position.
Having gone on to take the lead, White then won the second frame without conceding a point, confirming that the defending champion was under serious pressure.
With O'Sullivan misfiring from range and careless when in the balls, opportunities kept coming for the Whirlwind and the task at the end of frame three could hardly have been simpler, after O'Sullivan's reckless cut on the black left the frame ball over the pocket.
At 3-0, White was finally an odds-on favourite and how he should have capitalised. Granted, the fourth frame was never there to be won - O'Sullivan kicked into gear at last with a fluent 74 - but frames five and six certainly were, a missed black in the latter providing particularly costly.
And then, just as it seemed all hope had gone, White again found himself in among the balls and closing in on victory in the deciding frame, only to push a simple red and throw his cue to the ground.
O'Sullivan by now must have known his opponent was broken, and made sure that would be White's final contribution with a match-winning 76, the highest break of an engrossing, two-hour encounter which started with White rolling back the years, and ended in an achingly familiar fashion.
Thursday November 7
Afternoon session (1300 GMT)
TV coverage: ITV4
Group 1 semi-finals - best of seven
Evening session (1900 GMT)
TV coverage: ITV4
Group 1 final - best of 11