Leeds 33-26 St Helens
St Helens' Darren Smith scores past Leeds' Chris McKenna
Leeds are through to the Challenge Cup final after beating St Helens in extra-time in one of the most thrilling matches in the Cup's history.
Leeds roared into an 18-6 lead after 25 minutes with a brace of tries from leading scorer Mark Calderwood and one from co-winger Francis Cummins.
But the game swung St Helens' way following the introduction of Sean Long after 32
Darren Smith, Paul Newlove and Paul Sculthorpe all ran in tries to draw the Saints level.
St Helens thought they had booked a third successive final appearance when Smith's second try of the match gave them a 26-20 lead with just five minutes left of an epic tussle.
Tries: Cummins, Calderwood 2, McGuire 2
Goals: Sinfield 6
St Helens 26
Tries: Newlove, Sculthorpe, Smith 2
Goals: Sculthorpe 5
But a stoppage-time try from 20-year-old Danny McGuire, superbly converted from the touchline by skipper Kevin Sinfield, brought the first drawn semi-final for 15 years, taking the match into extra-time.
And, after St Helens substitute Mike Bennett had a try disallowed in the first minute of extra-time, the lead changed hands for a fourth time with Sinfield's drop goal.
McGuire finally settled a dramatic match after 100 minutes when he raced over for a second try to break the hearts of the champions.
After the game Leeds coach Daryl Powell paid tribute to his team's character.
He said: "It's unbelievable. I can't speak highly enough of them and I give all the praise
to the guys out there.
"They really stuck at it and Danny McGuire put it out of reach."
Leeds: Connolly, Calderwood, McKenna, Senior, Cummins, Sinfield,
Dunemann, Bailey, Diskin, McDermott, Walker, Adamson, Furner.
Replacements: Poching, McGuire, Ward, McDonald.
St Helens: Stewart, Albert, Gleeson, Smith, Newlove, Sculthorpe,
Wellens, Britt, Higham, Stankevitch, Joynt, Jonkers, Hooper.
Replacements: Long, Bennett, Edmondson, Ward.
Referee: R Smith (Castleford)