Kris Boyd's second-half goal gave Kilmarnock a 1-0 victory over his former club Rangers at Ibrox.
The veteran striker's 20th goal of the season, from close range in the 54th minute, was enough to take the Premiership points back to Ayrshire.
After losing to Old Firm rivals and league leaders Celtic last week to effectively end any pretence of a title race, it was another blow to Graeme Murty's side, who ran out of ideas.
Conversely, it was yet another impressive result for Steve Clarke's rejuvenated team, who beat Rangers 2-1 at Rugby Park in December having drawn 1-1 at Ibrox in October.
It was Kilmarnock attacker Eamonn Brophy who had the first attempt on goal, firing over from 20 yards in the second minute, but the Ayrshire side soon found themselves on the back foot.
Three minutes later Rangers midfielder Sean Goss floated a free kick from 25 yards past Kilmarnock goalkeeper Jamie MacDonald's left-hand post.
In the 10th minute, Rangers' Greg Docherty linked up with Jamie Murphy inside the Kilmarnock area but was denied by MacDonald as he stumbled getting his shot away, the Rugby Park keeper clutching Daniel Candeias' corner.
However, MacDonald should have been beaten midway through the first half when Goss picked out Russell Martin, in for the injured David Bates, with a wonderful cross, but the defender, six yards out, only glanced his header and the ball sped past the far post.
MacDonald then got a touch on the ball as striker Jason Cummings, in for Alfredo Morelos, stabbed a shot towards the goal from a Candeias pass, but on a bitterly cold day in Govan it was all very laboured.
And the Rangers fans let their side know about it when Brophy missed a Kirk Broadfoot cross a few yards from goal just before the break.
Goss was replaced by Jason Holt for the start of the second half, but the visitors should have taken the lead three minutes in when Jordan Jones got to the byline and cut the ball back for Brophy. He sliced his shot wide from 12 yards.
However, Kilmarnock did take the lead when keeper Wes Foderingham could only palm a Youssouf Mulumbu shot into the path of Boyd, who knocked it over the line from a couple of yards with his last piece of action before being replaced by Rory McKenzie.
Alan Power came on for Aaron Tshibola, with Morelos coming on for Josh Windass to partner Cummings as the home supporters became increasingly agitated.
Kilmarnock threatened to double their lead on a couple of occasions, while for Rangers it was huffing and puffing with Kenny Miller on for Candeias in a desperate last throw of the dice.
In the 77th minute, Martin header's from a James Tavernier free kick hit the bar before being scrambled to safety, but the visitors did not have to withstand any concerted pressure and indeed retained their threat on the counter attack.