St Johnstone moved above Kilmarnock in the Scottish Premiership after Makenzie Kirk's goal inflicted a third successive defeat on the Ayrshire side.
The Northern Irish striker produced a neat glancing header to nod in Andre Raymond's excellent delivery and earn St Johnstone's first victory in four league matches.
Kirk had spurned the only opportunity of an uneventful first half when his header from a Graham Carey cross dribbled harmlessly wide of Robby McCrorie's goal.
However, eight minutes into the second period, the youngster made amends when he found the net with his second sight of goal.
Kilmarnock still had more than 35 minutes to find an equaliser but failed to trouble Joshua Rae's goal.
Any hopes of a late resurgence were then extinguished when Derek McInnes's side were reduced to 10 men for the sixth time this season with just six minutes to play.
Liam Donnelly was shown a second yellow card by referee Iain Snedden for a high boot in the middle of the park.