As had been the case against St Johnstone last weekend, the Light Blues struggled to create and convert chances in front of goal in Ayrshire.
And they paid the price for that in the closing stages as home captain Manuel Pascali nodded in to blow the title race wide open again.
Gers are still top of the table by four points and have a decent advantage over Celtic as December approaches.
But after Killie celebrated this victory like a World Cup win, there is a definite need to lift their tempo once more after five dropped points in two matches.
Carlos Bocanegra missed out with a hamstring knock and Ross Perry replaced him while Sone Aluko made his debut on the right side of a three-man attack.
And the former Aberdeen man’s first contribution almost led to the opening goal as he played in Steven Davis in the opening couple of minutes.
The captain then centred for Nikica Jelavic but he couldn’t connect properly and when Aluko fed the Croatian moments later he hit the post but was flagged offside in any case.
Gers started really brightly and while there was no repeat of the 3-0 lead they stormed into in the first seven minutes at Rugby Park last time they were there, they looked a real threat.
Their impetus soon dipped but good hustling from Jelavic nearly resulted in a goal as he charged down keeper Cammy Bell and forced a throw in.
Defensively, Aluko was unlucky at times but whenever the away side poured upfield, he was at the heart of what they did and his shot midway through the first half was deflected wide.
And while Killie kept probing any time they came forward, it was the Ibrox outfit which appeared more purposeful as both tried to break the deadlock.
Yet as half-time approached, the balance of play swung a little and after Kyle Lafferty’s game ended early because of a back injury, there were claims for a home penalty.
Referee Alan Muir correctly waved them away though as Kirk Broadfoot’s tackle on Gary Harkins was perfectly timed as the forward homed in on goal.
Kane Hemmings, on for Lafferty, had a go from long distance seconds before the interval and forced Bell to parry away.
And Lee McCulloch could only fire into the side netting after a scramble in the six-yard box before the whistle went.
Rangers continued to press after the restart and good work by Davis set up Maurice Edu but he cut back when he should have shot and the chance was gone.
Play began to open up and both sides looked a little stretched when they were on the back foot so you sensed a goal was coming soon.
And Killie very nearly got it when Harkins raced clear and his shot – partially blocked by Steven Whittaker – almost sneaked in.
Instead it trundled behind for a corner and when that came over, Dorin Goian headed against his own bar before the danger was finally cleared.
The chances gave Kilmarnock confidence – but Gers came storming back and Liam Kelly had to hammer off the line after Hemmings had set up Aluko.
At the other end, it took a phenomenal save from Allan McGregor to save from Paul Heffernan when he broke the offside trap.
Jelavic had a chance to shoot from a 20-yard free kick when Whittaker was brought down but his effort hit the wall while McCulloch blazed over seconds later.
With time starting to run out, it was beginning to look like it might be one of those frustrating days for the away team as a ball in from Aluko smacked off the post.
And 10 minutes from the end, the Light Blues’ task got a whole lot harder as the Ayrshiremen went ahead through Pascali.
After a corner had only been partially cleared, Garry Hay’s innocuous ball back in appeared to be heading straight for McGregor’s grasp.
Pascali had stayed up though and an intelligent flicked header when Aluko played him onside floated over the keeper and in.
Gers threw everything they could at Bell’s goal in the final stages and substitute Alejandro Bedoya had their best chance but the keeper got down well to save.
That means the gap between the Old Firm team remains as it was going into the match and now the title race takes on a different look heading into the busy festive period.