Aberdeen leap-frogged Kilmarnock into the third place that brings European qualification with a 1-0 win at Rugby Park.
Prior to kick-off Kilmarnock had occupied that vital third spot in the Premiership as they led Aberdeen on goal difference.
A second half goal from Scott McKenna was enough to defeat eight man Kilmarnock and move three points clear of them.
McKenna’s goal was the difference in an ill tempered match where Killie defender Kirk Broadfoot was red carded in the first half for a reckless challenge on Joe Lewis.
Stuart Findlay was then sent off for a second yellow in the 84th minute for a second yellow awarded for a foul on Graeme Shinnie.
Killie completely lost their discipline and Rory McKenzie was red carded in injury time for lashing out at Dom Ball.
Aberdeen boss Derek McInnes made three changes to the side that finished with nine men in losing 3-0 to Celtic in the Scottish Cup semi-final.
Lewis Ferguson was ruled out through suspension as a result of his straight red at Hampden.
Also dropping out were 18-year-old midfielder Dean Campbell and the injured Greg Stewart.
Coming in were Stephen Gleeson, Mikey Devlin and skipper Graeme Shinnie who returned from suspension having been ruled out for the semi-final.
In the eighth minute Mikey Devlin picked up a yellow card for tripping Eamonn Brophy just inside the Dons half.
There were plenty of Aberdeen players in covering positions. It was a needless foul and booking and left the defender walking a disciplinary tight rope.
Moments later Scott McKenna came close when connecting with a Stevie May free-kick flighted deep towards the back post.
Scotland international defender McKenna rose well but his 12 yard header flashed across the face of goal and just inches wide.
In the 20th minute Kilmarnock threatened when Brophy fired in a half volley on the turn from 15 yards but Joe Lewis was well positioned at his near post to save comfortably.
Soon after Shinnie shot from the edge of the box but a deflection took the sting out of the effort and keeper Dan Bachmann gathered easily.
Referee Steven McLean failed to stamp his authority on this game and an ill tempered match with plenty bite but little beauty inevitably boiled over.
Aberdeen striker Sam Cosgrove fouled Gary Dicker in the 33rd minute.
As he lost his cool Cosgrove then fouled Stuart Findlay moments later and was fortunate not to receive a second booking.
That carried on with afters and Findlay then blatantly pushed Cosgrove in the box.
He was booked – and it could easily have been red. Findlay would later walk.
Moments later Killie were reduced to 10 men when Kirk BROADFOOT received a straight red in the 37th minute when the defender went in with his studs up into a challenge with keeper Joe Lewis who required treatment.
Dons boss McInnes replaced Cosgrove with James Wilson at half-time.
Despite Cosgrove’s goal threat it was a move to prevent him being sent off.
Early in the second half Wilson, on loan from Manchester United, met a cross from Connor McLennan but his header from the edge of the box sailed over.
Aberdeen went ahead in the 67th minute when MCKENNA latched onto a drilled corner from Shinnie.
The defender got ahead of Findlay and headed home from the six yard line.
In the 74th minute O’Donnell broke in on goal but substitute Ethan Ross made a superb back tracking run to deflect his shot wide for a corner.
Kilmarnock were reduced to nine men in the 84th minute when Findlay received a second yellow for a challenge on Shinnie.
Dons captain Shinnie received treatment for a number of minutes on the pitch before continuing.
Kilmarnock were reduced to eight men in injury time when Rory McKenzie was red carded for lashing out at Dom Ball.
ABERDEEN: Lewis, Shinnie, Considine, McKenna, Gleeson, Cosgrove, May, Devlin, Ball, McLennan, Lowe.
Subs: Wilson (for Cosgrove 46), E. Ross (for Devlin 65), Halford (for McKenna 82)
Subs not used: Cerny, Campbell, Dangana, Virtanen.
KILMARNOCK: Bachmann, O’Donnell, Broadfoot, Findlay, Taylor, Power, Dicker, Mulumbu, McKenzie, Burke, Brophy.
Subs :McAleney (for Burke 68), Millar (for Mulumbu 78), Boyd (for Brophy 78).
Subs not used: MacDonald, Bruce, Ndjoli, , Millen.
Referee: Steven McLean