Alfredo Morelos climbed off the bench to score the goal which keeps Rangers right behind Celtic heading into Sunday's Old Firm clash.
With his colleagues struggling to open up Alex Dyer's stuffy Kilmarnock, the Colombian made himself the hero within minutes of replacing Jermain Defoe as he fired his 28th goal of the season to clinch a 1-0 win.
The result means Rangers now travel to Celtic Park this weekend five points behind their bitter rivals but with a game in hand.
Morelos was free to face Killie after serving a one-match ban for his Fir Park dismissal but boss Steven Gerrard chose to start with Defoe up top following his goal in Friday night's win at Hibernian.
But the veteran Englishman found it hard going against a Killie team looking much more comfortable with caretaker boss Dyer in charge.
Killie took points off Rangers in four out of their five league visits to Ibrox under Steve Clarke and Gerrard predicted Dyer would revert to the game plan he helped implement to such success during the current Scotland manager's spell at Rugby Park.
And he was quickly proved correct as the visitors settled into their trusty 4-2-3-1 formation, making it clear it was up to the Light Blues to break them down.
However, Dyer had veteran defender Alex Bruce to thank twice inside the opening 20 minutes.
First he got his ageing limbs in the way to block a Defoe shot before doing the same to a Joe Aribo effort after Connor Goldson had sent Ryan Kent scampering forward with a delicious 45-yard diagonal pass.
Killie keeper Laurentiu Branescu began his time-wasting just 10 minutes in and it did not appear his side were too keen on getting alongside lone striker Liam Millar to offer support.
The one chance they did create during the opening period came moments after Branescu first drew himself to the attention of the tetchy home support as he took his time lining up a goal-kick.
Kilmarnock worked the ball wide to Nicholas Hamalainen, whose strike deflected off James Tavernier only for Millar to fail to connect at the back post.
With Dyer's men happy to sit in, the Rangers fans' impatience could be heard as the seconds ticked towards half-time. Glen Kamara thought he had hushed them on 43 minutes as he let fly from the edge of the box, only to see his dipping strike clip the top of the crossbar.
Referee Steven MacLean ordered Branescu to get a move on after the Romanian dawdled on his first kick-out of the second half.
The keeper was down in a hurry soon after, however, as he caught a Borna Barisic strike as Rangers worked it to the Croatian on the edge of the box from a corner. His save from a swerving Ryan Kent shot was even more impressive.
Gerrard decided enough was enough on 58 minutes as he replaced Defoe with Morelos.
And his top-scorer duly provided the winner within seven minutes of his introduction.
Kamara and Jack combined on the edge of the box before the latter picked out Aribo in the crowded box. The Nigeria international could have gone himself but squared it for Morelos in a better position and he did the rest.
Unsurprisingly the goal sparked Killie into a change of approach as they finally looked to get forward.
But that left room for Rangers to exploit on the counter and they should have extended their lead late had it not been for some poor decision-making from the likes of Morelos and Greg Stewart.
