James Wade held his nerve to come through a dramatic sudden death leg and clinch a thrilling 5-4 victory over John Part in a World Championship classic at Alexandra Palace.
Wade seemed to be in control of the quarter-final as he comfortably moved into a 3-1 lead, with Part winning only three of the first 17 legs.
However, the three-time world champion came roaring back to lead 4-3 and had the darts in the eighth set as he threw for the match.
But Wade levelled and then, after a memorable ninth and final set had gone all the way to five legs all, retained his composure to check out 85 in clinical style and seal victory.
There were few clues to the drama that lay ahead early on as Wade raced through the first set without dropping a leg.
Part did respond by taking the second in the deciding fifth leg with a stunning 167 check-out, but Wade raised his level and took the next two sets for the loss of just one leg and looked to be cruising.
Crucial 97 finish
But the Canadian gave himself renewed belief as he hit a crucial 97 finish to pinch the fifth set and stylish check-outs of 116 and 75 saw him square the match at 3-3.
An enthralling seventh set saw Wade move two legs to one ahead with a 12-darter, but Part levelled and then hit tops after his opponent had missed the same double to move 4-3 ahead overall.
A timely break at the start of the eighth helped Wade to take the set and force a decider which veered first one way and then the other.
Having taken out 124 to move 3-2 ahead in legs, Wade missed two darts for the match allowing Part to hit double-two to stay alive.
The Canadian then broke for a 4-3 lead, only for Wade to hit back immediately with a 108 finish which he then followed with a 12-darter to move 5-4 ahead in legs.
Fittingly Part forced a sudden death leg with a 13-dart leg of his own but, after Wade had got the darts by hitting bull, it was the Englishman who won out with an ice-cool two-dart finish of 85 with his opponent waiting on 40.
'The Machine' will now face defending champion Adrian Lewis, who saw off the challenge of Terry Jenkins by a 5-3 scoreline in Friday's evening session.