Celtic will meet Motherwell in the Scottish Cup final next month after easing past 10-man Aberdeen here yesterday.
Dons defender Andrew Considine handed the initiative to Neil Lennon's side in the 18th minute when he was sent off by referee William Collum for fouling Gary Hooper in the box, although goalkeeper Jamie Langfield saved Anthony Stokes' penalty.
Aberdeen held out until the break but the numerical disadvantage took its toll in the second half as goals from Charlie Mulgrew, Joe Ledley, Kris Commons, with a spot-kick, and Shaun Maloney, sealed a comfortable and expected win for Celtic.
Craig Brown's side went in to the game having conceded 17 goals to the Hoops in four previous games this season, including a 4-1 defeat in the semi-final of the Co-operative Insurance Cup at the end of January.
The first 45 minutes saw Celtic struggle to get past a solid Aberdeen rearguard, however all Langfield's good work was undone in the 49th minute. He looked at fault when Celtic took the lead through Mulgrew with a 25-yard free-kick into the box which evaded everyone in the box and caught Langfield off guard as it sped in at the far post.
In the 57th minute Celtic confirmed their appearance in the final when Ledley latched onto a Stokes cross to beat Langfield from 12 yards. Five minutes later Derek Young conceded a penalty when he brought down Stokes almost on the byline and this time Commons sent Langfield the wrong way from the spot. Maloney made it four with six minutes to go.
Lennon agreed Considine's sending off was the turning point and thought it was harsh. "Psychologically for Aberdeen it was damaging," he said. "But I do think it was a penalty and in the interpretation of the laws of the game, the referee probably had no choice but to send him off. I think it is one rule that could be doing with being looked at." Brown added that his defender was "distraught" afterwards.
Aberdeen (4-4-2): Langfield; Young (Vujadinovic, 65), Diamond, Considine, Smith; Magennis (Blackman, 61), Jack, Milsom, Aluko; Maguire, Vernon (Paton, 78). Substitutes not used: Howard (gk), Robertson.
Celtic: (4-3-1-2): Forster; Wilson, Rogne, Mulgrew, Izaguirre; Brown, Kayal (McCourt, 61), Ledley (Maloney, 69); Commons; Hooper (Majstorovic, 79), Stokes. Substitutes not used: Zaluska (gk), Forrest.
Referee: W Collum (Scotland).