Barry Hawkins survived a remarkable fightback from Dominic Dale to seal a 13-12 victory and set up a semi-final against defending champion Ronnie O'Sullivan at the Dafabet World Snooker Championship.
Dale, trailing 11-5 overnight, claimed the first seven frames of the session to shock last-year's runner-up who needed just two further frames when play began on Wednesday afternoon.
He eventually got them, but they were the last two of the session as Hawkins set up a repeat of last year's final.
Dale took the first three frames of the day with breaks of 75, 65 and 64 before claiming a slightly scrappier encounter to go into the mid-session interval just two behind.
A break of 61 in the 21st made it 11-10 and the Welshman then prevailed from a long safety battle to level up the scores.
A 52 clearance in the next edged the player known as 'Spaceman' ahead and at that point it looked like momentum would carry him over the line but Hawkins is made of stern stuff and claimed his first frame of the day with a break of 66 took the match to a decider.
Both players were edgy in the opening stages but it was Hawkins who held his nerve with a 65 clearance to go through.
In tonight's quarter-final, Neil Robertson progressed to the semi-finals beating Judd Trump 13-11.
Trailing 6-2 when the day started, Robertson dominated the early going to get it back to 7-6, but Trump kept digging in to stay in front and was 9-6 up at the interval.
Robertson once again closed the gap to a frame before Trump won the next two to open up an 11-8 lead.
From there it seemed there would be only one winner but Robertson fought back valiantly and closed the gap to just one frame for a third time with some attritional play before levelling proceedings with a landmark 101 break, celebrating with a huge pump of the fist.
The body language told the story on both sides with Trump looking like he would rather be anywhere else as Robertson moved 12-11 ahead.
The Bristol man had good cause as his scoring drought moved into a second hour, only ending when Robertson gifted him four with a foul to make it 43-4 in the 24th frame.
That offered him a way back in but having pulled within eight, Trump missed what should have been a routine black and Robertson made him pay by closing out the match.