A bid of £3.75 million from Bordeaux for the Colombian striker was rejected out of hand by the Ibrox club last week and manager Gerrard’s determination to retain his services will only have hardened after this contribution.
Morelos struck twice before half-time then sealed victory for Rangers in the closing stages after an own goal from Croatian defender Borna Barisic had given Kilmarnock hope of salvaging the second round tie.
Gerrard’s buoyant team are now unbeaten in nine competitive outings since his summer arrival and will look to carry that momentum into the first leg of their Europa League play-off tie against Russian side Ufa on Thursday.
Morelos would have experienced a sense of justice being done as he put Rangers in command at Rugby Park, having been denied what he claimed was a legitimate goal as early as the seventh minute.
Kilmarnock, not for the last time in the afternoon, were undone down their left flank as James Tavernier and Ryan Kent combined to set up the opportunity for Morelos. He was unable to get as much purchase as he would have liked on his close range effort but seemed to have done just enough to force the ball over the line before Stephen O’Donnell booted it away.
But to the dismay of Morelos, not to mention the Rangers fans behind the goal, assistant referee Daniel McFarlane ruled otherwise and the scoreline remained blank.
If that was a reprieve for Kilmarnock, they set out to take full advantage of it and almost snatched the lead themselves five minutes later. Wes Foderingham, making his first appearance of the season for Rangers as midweek Europa League hero Allan McGregor was rested, had to react sharply to touch over a free-kick from Chris Burke which may have been intended as a cross but was curling towards the keeper’s top left hand corner.
There was a blow for Rangers when Jamie Murphy, pursuing a through ball with Kirk Broadfoot, seemed to jar his left leg on the artificial Rugby Park surface and slumped to the ground in obvious distress.
Murphy was led away on a stretcher and replaced by Daniel Candeias, the substitution seeing Kent switch to the left flank.
Daniel Bachmann, making his debut in goal for Kilmarnock following his loan move from Watford, did well to keep out a close range Morelos shot after the striker had been played in by Candeias.
It was an open cup tie with play ebbing and flowing as Kilmarnock showed plenty of attacking ambition of their own. Burke came close with another free-kick in the 25th minute, cheaply conceded by Tavernier, when his driven effort was met with an outstanding reflex save by Foderingham who turned the ball over.
It proved to be a significant contribution from the now back-up goalkeeper as Rangers took the lead three minutes later. It was the best move of the tie so far from Gerrard’s men with Scott Arfield, Andy Halliday and Candeias all involved as they created space on the right for Tavernier. His perfectly weighted cross was headed home from close range by Morelos.
Kilmarnock’s response to the setback was positive and they came close to an equaliser in the 33rd minute when another fine set piece from Burke, this time a corner from the left, picked out Broadfoot whose header clipped the top of the crossbar.
The hosts could consider themselves a little unfortunate to be behind on the balance of play at this stage but Rangers tightened their grip on proceedings when Morelos grabbed his second goal two minutes before the break. It was excellent centre forward play from the 22-year-old, using his strength to turn away from Scott Boyd inside the penalty area and latch onto Tavernier’s through ball before drilling a right foot shot across Bachmann into the far corner of the net.
Rangers opened the second half with purpose and swagger, moving the ball around with pace and precision, but they were knocked out of their stride when Kilmarnock pulled a goal back in the 51st minute. Jordan Jones broke free on the left and his dangerous cross, intended for Kris Boyd, was turned into his own net by Borna Barisic.
The tie was now firmly back in the balance and Bachmann ensured it remained that way for a significant period, the Austrian ‘keeper producing a string of fine saves to defy efforts from Morelos - twice- and Arfield as Rangers decided that attack was the best form of defending their lead.
That approach paid off in the 74th minute when they restored their two-goal cushion and Morelos celebrated his personal treble. It was the simplest finish of the lot as he tapped home from inside the six yard box after being picked out by Tavernier’s cross.
Foderingham made another smart stop to keep out a Kris Boyd header and ensure Rangers enjoyed a reasonably stress-free conclusion to the contest, albeit Connor Goldson was fortunate not to concede a stoppage time penalty for a push on the veteran Killie striker.
KILMARNOCK: Bachmann, O’Donnell, Broadfoot, S.Boyd (Ndjoli 80), Taylor; Burke, Dicker, Power (Wilson 80), Jones; Brophy, K.Boyd. Subs not used: MacDonald, Kiltie, Waters, Graham, Cameron.
RANGERS: Foderingham, Tavernier, Goldson, Katic, Barisic; Halliday, Ejaria, Arfield (McCrorie 79); Kent, Morelos (Sadiq 79), Murphy (Candeias 17). Subs not used: Alnwick, Jack, Flanagan, Middleton.