Rangers survived an early scare against Ayr United to cruise into the Scottish Cup quarterfinals with a thumping 6-1 win at Somerset Park.
Alan Forrest, brother of Celtic winger James Forrest, took advantage of a mistake by Gers goalkeeper Wed Foderingham to give the League One side a shock lead in the 10th minute before returning striker Alfredo Morelos levelled on the half-hour.
Graeme Murty's side were ruthless after the break as Jason Cummings struck from close range in the 65th minute before a double from Josh Windass, either side of Morelos' second, preceded a last-minute counter from Jamie Murphy.
The home side's early goal which had given them hope was a calamity for the visitors.
Foderingham hesitated when taking David Bates' pass back and Forrest closed the keeper down and bundled the ball into the net.
It was the perfect start for United, whose manager Ian McCall missed the match after undergoing an operation for a detached retina last week as assistant manager Neil Scally took charge.
The goal sprung Rangers into action and they upped the tempo immediately, forcing Ayr into some dogged defending.
In the 25th minute, Windass' header from a James Tavernier cross crashed off the crossbar before Morelos scooped a Greg Docherty cross over from a couple of yards out.
It was a remarkable miss but the Colombian striker made up for it a few minutes later as he fired high into the net after midfielder Sean Goss's 25-yard drive cannoned off the bar.
Gers kept up the pressure and as the driving sleet turned to snow Ayr keeper Jack Ruddy parried a Cummings drive from close range.
There was a delay to the start to the second-half as lines were cleared of snow.
Rangers kept pressing but Foderingham was forced into a good blocking save from Declan McDaid following a swift Ayr counter-attack.
Goss came close with a drive before Murphy had the ball in the Ayr net on the hour mark after Ruddy had spilled a powerful shot from Cummings only to see the offside flag go up.
The next goal looked imminent and it arrived when Murphy took a quick corner to Goss and Cummings managed to hook the cross over his shoulder and into the net.
Rangers pressed home their superiority as Windass side-footed a Declan John cut-back into the net from 14 yards before Morelos did likewise from much closer range after being set up by Murphy.
Windass completed his double with back-post header from another Goss delivery before Murphy, on loan from Brighton, scored his first goal for Rangers with a fine angled finish.