Luke Gale fired over the winning drop goal as Castleford Tigers claimed a 23-22 golden-point victory over St Helens in an enthralling Super League semi-final at the Jungle on Thursday.
Daryl Powell's men have been the dominant force in English rugby league this season, having already lifted the League Leaders' Shield for the first time in their history, and looked to be on their way to the Grand Final after opening up a 20-10 lead midway through the second half.
But Saints sensationally pulled back and, but for the wayward kicking of Mark Percival, would have snatched away their hosts' ticket to Old Trafford.
A Gale penalty after the hooter drew the teams level at 22-22 to force the additional period and the Tigers' talisman was then on hand to deliver the decisive blow to Saints' hopes and keep Castleford's dreams of a maiden Super League crown alive.
The match started brightly for Cas, as Zak Hardaker crossed for the first try inside a minute, with Gale adding the extras and converting a subsequent penalty to open up an 8-0 lead.
Saints soon found their feet and Welsh winger Regan Grace crossed in the corner to reduce the deficit, but Percival's missed conversion was an unfortunate sign of things to come for the visitors.
The centre was on target with his next kick to move Saints into a 10-8 half-time lead after Morgan Knowles crossed under the posts, before Gale converted his own try to hand the advantage back to Cas after the interval.
Adam Milner looked set to be the match winner when he produced a try-saving tackle to stop Tommy Makinson and then touched down himself as the home side moved 20-10 in front.
But there was still plenty of life left in the encounter, and Makinson and Percival scored a try apiece to set up a grandstand finish, although the latter was unable to convert either with kicking form that would come to prove costly.
He was off target again after Ryan Morgan touched down to seemingly clinch victory three minutes from time, but the try scorer turned villain when a tackle off the ball on Michael Shenton opened the door for Gale to force golden point - an opportunity he duly grasped from the tee.
And, after half-chances for drop goals from Gale and Matty Smith, it was the former - still sporting the bandages from recent appendix surgery - who split the posts to ensure Cas have the chance to write a successful final chapter to their season.
Leeds Rhinos or Hull FC await the Tigers in the Grand Final.