St Johnstone won a dour encounter at McDiarmid Park to move into fourth place in the Scottish Premier League.
Saints had the best chance of a poor first-half, Killie keeper Cammy Bell deflecting a Steven MacLean shot wide.
The home side took the lead when Murray Davidson slotted the ball home from close range as the Killie defence failed to clear a corner.
Kilmarnock couldn't find a way past the Saints defence and Gregory Tade's late header sealed the victory.
Both Steve Lomas and Kenny Shiels had targeted 47 points as the figure they needed to make the top six and therefore this was a big three points for St Johnstone.
The home side were better throughout and had the best of a fairly dull first period which saw Rowan Vine fail to take two real chances - the first when his shot was blocked and the second when he blasted wildly over the top from 12 yards after good set up play from Murray Davidson.
However, the best chance of the half fell to Steven MacLean when he was played in by Hasselbaink but Killie keeper Cammy Bell blocked his shot and the ball drifted just past the post.
Kilmarnock had been forced to hit on the break and William Gros had a shot saved by Alan Mannus in the Saints goal and Ross Barbour shot high and wide after a good run, but the 2425 people who had braved the cold to watch the game were far from happy and there was muted boos as the sides left the pitch at the interval.
The pattern continued after the break and Sammy Clingan fired a shot just past the post for the visitors before the home side took the lead on 57 minutes.
Dave Mackay's charging run and shot was deflected wide and Liam Craig's deep corner was not dealt with by the Kilmarnock defence and fell to Murray Davidson who blasted home his seventh goal of the season from eight yards.
Craig's delivery was to make all the difference again as Saints clinched the points five minutes from time, when his deep cross found substitute Gregory Tade free in the box and he flashed a header from eight yards past the keeper for his fifth goal of a frustrating season.
Killie boss Shiels was waiting for answers from his defenders about the loss of both goals long after the match, but the home side go into a three-week break with high hopes of a top-six finish and some of the fans even dreaming of another shot at Europe.
Live Text Commentary
Full Time The referee signals the end of the game.90:00 +2:45
James Dayton challenges Liam Craig unfairly and gives away a free kick.90:00 +2:00
Corner from right by-line taken by Liam Craig.90:00 +1:25
Kris Boyd takes a shot. Alan Mannus makes a comfortable save.90:00 +1:13
James Dayton produces a cross.89:57
The referee blows for offside. Free kick taken by Cameron Bell.89:23
Free kick awarded for an unfair challenge on Sammy Clingan by Mehdi Abeid. Cameron Bell takes the indirect free kick.88:36
Corner taken left-footed by James Dayton from the left by-line, Murray Davidson makes a clearance.87:24 Substitution
Substitution Gwion Edwards replaces Steven MacLean.86:41
James Fowler concedes a free kick for a foul on Chris Millar. Direct free kick taken by Liam Craig.84:59
The assist for the goal came from Liam Craig.84:59 Goal scored
Goal! - Gregory Tade - St J'stone 2 - 0 Kilmarnock Gregory Tade finds the net with a headed goal from inside the six-yard box. St Johnstone 2-0 Kilmarnock.84:43
The ball is crossed by Liam Craig,82:59
Steven MacLean gives away a free kick for an unfair challenge on Garry Hay. Direct free kick taken by James Dayton, Liam Craig takes a shot. Comfortable save by Alan Mannus.81:46
Inswinging corner taken from the left by-line by Mehdi Abeid, clearance made by Sammy Clingan. Mehdi Abeid takes the inswinging corner, James Fowler makes a clearance.79:48
Free kick taken by Sammy Clingan.79:48 Substitution
Substitution Nigel Hasselbaink leaves the field to be replaced by Mehdi Abeid.79:48
Gregory Tade concedes a free kick for a foul on Ross Barbour.77:20
Effort on goal by Murray Davidson from just inside the box goes harmlessly over the target.75:44
Direct free kick taken by Sammy Clingan.
Substitution Kris Boyd replaces William Gros.75:44 Booking
Booking Liam Craig is shown a yellow card for unsporting behaviour.75:38
Free kick awarded for a foul by Liam Craig on James Dayton.74:49
William Gros takes a shot. Save made by Alan Mannus.70:46
Liam Craig delivers the ball.68:37 Substitution
Substitution Gregory Tade comes on in place of Rowan Vine.67:55
Rowan Vine decides to take a short corner.67:29
The referee penalises Nigel Hasselbaink for handball. Garry Hay takes the free kick.66:25
The ball is swung over by Cillian Sheridan, clearance made by Callum Davidson. Inswinging corner taken from the right by-line by James Dayton, Callum Davidson makes a clearance.63:51
Indirect free kick taken by Liam Craig.63:51 Booking
Booking James Fowler shown a yellow card.63:33 Substitution
Substitution Garry Hay on for Jeroen Tesselaar.63:33 Substitution
Substitution Jude Winchester goes off and Cillian Sheridan comes on.63:33
Foul by James Fowler on Chris Millar, free kick awarded.61:48
Alan Mannus restarts play with the free kick.61:48 Booking
Booking James Dayton is cautioned.61:39
James Dayton gives away a free kick for an unfair challenge on Murray Davidson.59:40
Corner from the left by-line taken by James Dayton, clearance by Chris Millar.57:18
Assist on the goal came from David McCracken.57:18 Goal scored
Goal! - Murray Davidson - St J'stone 1 - 0 Kilmarnock Murray Davidson scores a goal from close range low into the middle of the goal. St Johnstone 1-0 Kilmarnock.56:56
Inswinging corner taken from the right by-line by Liam Craig,55:33
Inswinging corner taken from the right by-line by James Dayton, Alan Mannus makes a save.53:20
Inswinging corner taken left-footed by Liam Craig from the right by-line, Mohamadou Sissoko makes a clearance. Short corner worked by Rowan Vine.51:58
Handball decision goes against Murray Davidson. James Fowler restarts play with the free kick.51:17
Foul by James Dayton on Nigel Hasselbaink, free kick awarded. Alan Mannus takes the free kick.49:20
Rowan Vine takes a shot. Blocked by Ryan O'Leary. Inswinging corner taken by Rowan Vine, Callum Davidson gives away a free kick for an unfair challenge on William Gros. Cameron Bell takes the free kick.48:29
David MacKay crosses the ball.45:39
Unfair challenge on Ross Barbour by Rowan Vine results in a free kick. James Fowler crosses the ball from the free kick right-footed from right by-line.45:01
The referee gets the second half started.45:00 +0:36 Half time
Half Time The referee blows for half time.43:07
Free kick awarded for an unfair challenge on Ross Barbour by Rowan Vine. Direct free kick taken by Sammy Clingan.41:36
The ball is crossed by David MacKay, free kick awarded for an unfair challenge on Ross Barbour by Rowan Vine. Cameron Bell takes the free kick.40:53
Liam Craig sends in a cross, Cameron Bell makes a save.39:13
Liam Craig takes the inswinging corner, clearance by Ryan O'Leary.38:28
Murray Davidson gives away a free kick for an unfair challenge on James Dayton. Direct free kick taken by Ross Barbour.35:06
The referee blows for offside against Steven MacLean. Cameron Bell restarts play with the free kick.34:05
Paul Heffernan gives away a free kick for an unfair challenge on David McCracken. Steven Anderson takes the indirect free kick.33:30
James Dayton decides to take the corner short.31:52
Steven MacLean takes a shot. Cameron Bell makes a save. Corner taken by Rowan Vine, Sammy Clingan makes a clearance.25:21
Effort on goal by Chris Millar from deep inside the area goes harmlessly over the bar.24:10
The ball is crossed by Sammy Clingan, save by Alan Mannus.22:41
Free kick awarded for an unfair challenge on Ross Barbour by Chris Millar. Ryan O'Leary takes the free kick.21:47
David MacKay sends in a cross.19:47
Effort on goal by Ross Barbour from outside the penalty box goes harmlessly over the bar.18:58
Liam Craig takes a shot from just inside the penalty box which clears the crossbar.17:05
Liam Craig delivers the ball, clearance by Mohamadou Sissoko.15:04
Paul Heffernan concedes a free kick for a foul on Steven Anderson. Callum Davidson takes the free kick.10:58
Corner taken by Liam Craig from the right by-line, Cameron Bell makes a save.8:18
William Gros takes a shot. Alan Mannus makes a save.3:43
Ross Barbour crosses the ball, clearance made by David McCracken.1:03
Rowan Vine takes a shot. Clearance made by Nigel Hasselbaink.0:22
The official flags Steven MacLean offside. Cameron Bell restarts play with the free kick.0:00
The referee starts the match.
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