After the away side opened the scoring inside six minutes, the young Gers responded with purpose to complete the turnaround before the half-time interval through a well-taken Kyle Glasgow brace.
Rangers then ratcheted up the intensity in the second period, adding a third through Cameron Fernie before fellow substitute Chris Condy capped off a flowing move four minutes from time to round off a convincing triumph.
Stevie Smith named six changes to his young side from last week’s KDM Evolution Trophy clash against Annan Athletic, with the 15-year-old duo of Glasgow and Ashton Scally given the nod from the off.
It wasn’t quite the start that Rangers sought when, just six minutes into the contest, the Ayrshire outfit broke the deadlock.
Indeed, the Gers had rode their luck minutes before when Remo Margiotta sprung the offside trap and forced a smart stop from Rydnn McGuire, but the Gers No.1 was soon picking the ball out the back of his net.
It was Margiotta whose smart run prompted danger in the home side’s ranks, doing well to fight off a succession of Rangers challenges inside the penalty area before laying the ball back to Adam Law who sidefooted beyond McGuire.
The hosts took a while to get into their groove from an attacking perspective, but when they did they restored parity on 18 minutes with a free-flowing move.
Scally was the beneficiary on the left-hand side when he was released into space in the final third, lifting his head to pick out Glasgow lurking 15 yards out who swept a delightful finish first-time into the bottom corner.
Making his first Under-19s start was Zebedee Lawson, who joined from Brighton & Hove Albion earlier this month, on the right-hand side of the attack, with the winger unleashing at goal moments later when he rode a tackle in midfield and shot off target from 25 yards out.
Still, the warning sides remained for the Gers defence when Margiotta squeezed his way through under pressure from James Reid, although the defender did just enough to disturb the Killie forward who could only poke his effort against McGuire.
However, the first-half turnaround was complete for the hosts just beyond the half-hour mark. Killie appeared under little pressure, but a short back pass from Josh Gilmour was pounced upon by the impressive Glasgow who rounded the goalkeeper and slotted into an empty net from close range.
Despite the superiority in the scoreline, Smith would have still sought greater control from his side given Killie’s threat going forward.
Archie Traynor went close twice in a six-minute period for the visitors, dragging an audacious effort wide from distance before contriving to strike the side netting from close-range when a delivery from the right-hand side travelled untouched through the Gers penalty area.
The second half began with McGuire making an outstanding reflex save to deny Duncan Barlow’s close-range header. The offside flag was raised against the Killie defender, but it was to McGuire’s credit that he was completely unaware when sticking out a strong palm.
Minutes later, Calum Adamson drove down the opposite end and was cynically fouled 25 yards from goal. Free-kick duties were assumed by Callum Burnside whose curling effort drifted just wide of the goal.
Killie were picking their moments as Rangers poured forward in search of a third to spring forward quickly, releasing Cole Coughlin in-behind shortly after the interval whose low, driven effort was saved by the legs of McGuire.
A third goal looked certain for the hosts when Burnside sprung forward at lightning speed on the break, delaying a pass just in time to thread Cormac Christie through on goal whose left-footed strike was saved by the legs of Dylan Brown in the Killie goal.
However, the points were assured 17 minutes from time, and it would have been music to the ears of Stevie Smith whose second half substitutes paid dividends.
Luca Rankin, another 15-year-old in Rangers colours, was only on the pitch a matter of minutes when he collected the ball in space at the edge of the penalty area. With no Killie defenders prepared to engage, the young midfielder slid a delicious pass through to fellow substitute Fernie who had the time and space to steady himself and plant a confident finish into the bottom corner.
There was still time for the young Gers to add a fourth of the evening in the dying embers, cutting through Killie at will thanks to a sumptuous reverse pass from Scally which was squared across goal by Burnside for substitute Chris Condy to tap home.
RANGERS: McGuire, Kerr, Hynd (Young, 80), J. Reid, Scally, McCallion (Fernie, 60), Adamson (Smith, 60), Glasgow, Lawson (Rankin, 67), Burnside, Christie (Condy, 80)
Subs not used: S. Reid, Owen
KILMARNOCK: Brown, Barlow (Feeney, 84), Craig, Spence, Gilmour, Traynor (Bickerton, 84), Simpson, Foster (Watson, 73), Margiotta, Law (Orr, 66), Coughlin (McMillan, 73)
Subs not used: Mullen, Sweeney
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