Match ends, Rangers 4, St. Mirren 0.
Rangers scored three of the four penalties they were awarded as they swept aside bottom side St Mirren to move to within three points of Scottish Premiership leaders Celtic.
James Tavernier slotted in after three minutes, but his second spot kick struck the outside of a post. The Rangers captain made amends with a third penalty after the break.
Tavernier passed up the chance of a hat-trick as Jermain Defoe scored the hosts' fourth spot-kick before Defoe set up Ryan Kent for a fine finish.
The win was enough to take Steven Gerrard's side closer to city rivals Celtic, who play St Johnstone on Sunday.
St Mirren, meanwhile, lose ground on both Hamilton Academical and Dundee, who drew at Hope Stadium.
Changes made, but same outcome
Gerrard had made eight changes for the second game in a row, with only January loan signings Defoe and Steven Davis, plus centre-half Nikola Katic, retaining their places after the midweek Scottish Cup win at Cowdenbeath.
It meant a return to the diamond midfield - with Defoe partnering Alfredo Morelos up front - that fell flat against Kilmarnock.
The formation appeared to deliver immediately as the on-loan Bournemouth striker won the opening penalty, which was dispatched by Tavernier for his 10th goal of the season.
St Mirren manager Oran Kearney had made 10 January signings as he looked to change his side's fortunes, but his only change from last week's defeat by Hibs was to return Anton Ferdinand to his defence.
Rangers, though, were awarded a second penalty by referee Andrew Dallas, with St Mirren disputing the suggestion of a foul on Defoe by Paul McGinn.
Tavernier's spot kick struck the outside of a post and the Paisley side avoided further damage until after half time as a Kent drive struck the bar.
Right-back Tavernier won - and scored - the third penalty himself, his cross striking Greg Tansey's arm, with the Paisley side left claiming that it had been outside the box.
Rangers were not finished yet as St Mirren's resistance crumbled despite the introduction of new signings Mateo Muzek, Laurentiu Corbu and Duckens Nuzon.
The visitors again disputed a penalty award against Tansey, claiming the midfielder's trip on Daniel Candeias was outside the area.
Rangers' own discussions led to Tavernier handing Defoe the chance to score his first goal at Ibrox and the former England striker duly obliged.
Goalkeeper Vaclav Hladky denied Defoe and Candeias, but Rangers were not to be denied a fourth as Defoe set up Kent for a neat chip over the advancing Czech.
As Rangers continue their challenge at the top, St Mirren slip two points behind Dundee, with Hamilton a point further ahead.
'We looked a bit lethargic' - reaction
Rangers manager Steven Gerrard: "I'm disappointed with the first-half performance. I thought we were a little bit off it.
"I thought we looked a little bit lethargic and forgot to do the basics that are required at football matches at a big club, which is to run hard, be aggressive, make tackles, do the ugly bits."
St Mirren manager Oran Kearney: "I had a good conversation with Andrew Dallas. There was no histrionics, I just asked his opinion. He hadn't watched the penalties back.
"We just kept getting things thrown at us. I suppose it is human nature to think, 'god, how are we ever going to get something out of this?' But there is one definite penalty, the first, and three that aren't."
- 17McCrorieBooked at 49minsSubstituted forJackat 54'minutes
- 10DavisSubstituted forCandeiasat 64'minutes
- 20MorelosBooked at 39mins
- 9DefoeSubstituted forLaffertyat 83'minutes
- 15BairdBooked at 26mins
- 2McGinnBooked at 44minsSubstituted forCorbuat 77'minutes
- 39ErhahonSubstituted forMuzekat 73'minutes
- 11JacksonSubstituted forNazonat 56'minutes
- Andrew Dallas
- Shots on Target
Second Half ends, Rangers 4, St. Mirren 0.
Attempt missed. Alfredo Morelos (Rangers) right footed shot from the right side of the box is just a bit too high.
Attempt saved. Ryan Kent (Rangers) left footed shot from the centre of the box is saved in the centre of the goal.
Kyle Lafferty (Rangers) wins a free kick in the defensive half.
Foul by Stephen McGinn (St. Mirren).
Attempt blocked. Duckens Nazon (St. Mirren) right footed shot from outside the box is blocked.
Foul by Borna Barisic (Rangers).
Laurentiu Corbu (St. Mirren) wins a free kick in the defensive half.
Substitution, Rangers. Kyle Lafferty replaces Jermain Defoe.
Goal! Rangers 4, St. Mirren 0. Ryan Kent (Rangers) left footed shot from the left side of the six yard box to the bottom right corner. Assisted by Jermain Defoe.
Goal! Rangers 3, St. Mirren 0. Jermain Defoe (Rangers) converts the penalty with a right footed shot to the top left corner.
Penalty Rangers. Daniel Candeias draws a foul in the penalty area.
Penalty conceded by Greg Tansey (St. Mirren) after a foul in the penalty area.
Ryan Jack (Rangers) wins a free kick in the attacking half.
Foul by Brad Lyons (St. Mirren).
Substitution, St. Mirren. Laurentiu Corbu replaces Paul McGinn.
Attempt blocked. Daniel Candeias (Rangers) right footed shot from outside the box is blocked.
Attempt saved. Alfredo Morelos (Rangers) left footed shot from the centre of the box is saved in the centre of the goal.
Attempt saved. Ryan Kent (Rangers) right footed shot from outside the box is saved in the centre of the goal.