Kemar Roofe fired Gers ahead with his 12th of the season before Morelos pounced for his first domestic goal since scoring against Hibernian back in September.

And his return to form could not be better timed for Rangers as they prepare to stretch their 16-point lead over second-placed Celtic even further when they host the second Old Firm clash of the season on Saturday.

Goodwin's side have now suffered just their second defeat in 10 games.

The Irishman was hoping lightning would strike twice as he went with the same team which shocked Rangers to end their 27-game unbeaten run a fortnight ago.

Gerrard gambled that night by leaving out a string of his key men but was taking no chances this time.

However, he did make two changes to the team which edged past Hibs on Boxing Day. Ryan Kent paid for his lack of productivity in recent weeks as the £7million man joined Leon Balogun on the bench, with Morelos and Filip Helander returning.

Complacency was at the heart of Rangers' troubles earlier this month and some more slackness in their play only offered the hosts encouragement.

Saints were even given a sight of goal inside the first 15 seconds as Steven Davis was robbed of possession but Jamie McGrath – who netted twice in that famous win – could only fire straight at Allan McGregor from distance.

Goodwin's team really should have scored in the 12th minute. Dylan Connolly took on a first-time shot from Richard Tait's cross which McGregor spilled back into traffic but Jon Obika hooked a golden chance wide.

It appeared to be going to plan for Saints, though, as they again refused to lie down to the league leaders. Davis was being forced to fire long passes from deep while Helander was clearly uncomfortable with the attention Connolly was paying him.

Rangers, however, have had a knack of making the most of opportunities when they matter most this term and that is how it proved after 27 minutes.

Glenn Kamara fed the ball into Ianis Hagi and the Romania international did brilliantly to hold off three Saints players before sliding in Roofe, who netted his 10th league goal in 11 starts with the help of a deflection off Conor McCarthy's boot.

Saints looked for an immediate reply as McGrath's low driven free-kick fell to Tait, who could only flick the ball wide.

And instead of being level, the Buddies found themselves two down as Joe Shaughnessy's suicidal back-pass left Morelos darting through on goal.

There was no sign of the self-doubt that has plagued the Colombian recently as he coolly slotted past former Ibrox team-mate Jak Alnwick to at last end his eight-game drought in all competitions.

Tait was well-placed at the back post to block a Hagi effort nine minutes into the second period as Rangers looked to put the win beyond doubt.

St Mirren were clinging in there so Gerrard switched from his trusted three-man midfield to a 4-4-1-1 as he looked to tighten things up in the final quarter.

Yet the Ibrox boss need not have worried as it was Saints that were forced to scramble clear again as McGrath headed Roofe's opportunistic flick away from under his own crossbar.

There were three in blue queuing up for a tap-in as Hagi then went wide past Alwnick but no one could get a toe to the ball as it fizzed across the face of goal.