Galway kingpins Corofin came through an endurance test in Castlebar beating Connacht holders Castlebar 0-17 to 0-14 after extra-time to reach a sixth provincial final in nine seasons.
Points from Michael Farragher, Micheál Lundy and Gary Sice (free) in the second period of extra-time proved decisive in a championship game that crackled throughout.
Man of the match Ian Burke, Michael Farragher and Jason Leonard finished with ten points between them for the North Galway men.
However, Castlebar relied far too heavily on their leading scorer, Neil Douglas, for scores and inspiration.
The diminutive attacker shot ten points (all but one from placed balls) but only one of Mitchels’ other starting forwards managed to score from play.
The two evenly-matched sides had finished deadlocked at 0-11 each after more than sixty attritional minutes.
Castlebar hit the front twice in the final quarter through Neil Douglas and David Stenson only to be pegged back each time by scores from Daithí Burke and Ian Burke.
The Galway champions then looked set to snatch victory when Ronan Steede landed the lead point in injury-time, but Mitchels substitute David Stenson grabbed an equaliser in the dying moments.
Corofin’s stylish attacker Ian Burke turned on the style in extra-time with two neat points to help the pre-match favourites into a 0-14 to 0-12 lead at the break.
All Castlebar could muster up in response in the final fourteen minutes were two frees from Neil Douglas.
St Brigid’s will face Corofin in the decider for the third time in 10 years after the Roscommon champs devoured Leitrim neighbours Aughawillan 2-18 to 1-7.
Goals from Darren Dolan and Brian Stack ensured that the 2013 All-Ireland champions were always in control as Senan Kilbride and Eoin Sheehy kicked points at their ease in a classy win.