Stephen Robinson
Former Motherwell manager on BBC Sportsound

All the pressure is coming from Rangers and Borna Barisic's cross finds Kemar Roofe at the front post, but the English striker can't get enough on his header and it is easy enough for goalkeeper Zander Clark.

Scott Tanser was also involved in thwarting Ryan Kent, but the St Johnstone left-back comes off worst and limps off, his game over.

Callum Booth is a straight replacement.

A great last-ditch challenge on the edge of the penalty box from St Johnstone midfielder Ali McCann denies a quick break from Ryan Kent for the concession of a corner.

James Tavernier is so close - twice within seconds.

The Rangers captain's cross-cum-shot is deflected just over and his own resulting corner evades a couple of boots at the front post and looks to be curling into the net.

However, goalkeeper Zander Clark scoops it off the line.

St Johnstone are defending ever deeper but have a good chance on the break with Ali McCann on the charge.

They have numbers up the pitch and, instead of finding a team-mate, he fires a tired drive well high and wide from 20 yards.

What a waste, as Ian Dury used to say.

Rangers get the first period of extra time under way.

Whose domestic double will still be on course by the end of it? The league champions or League Cup winners?

Tom English
BBC Scotland's chief sports writer

Indeed, we will need another 30 minutes - and maybe penalties - to decide the third side into the Scottish Cup semi-finals.

Rangers had the better of the chances, but St Johnstone are well in this game.

They have become the first Scottish side since Hamilton Academical on 4 March 2020 to prevent Rangers scoring in 90 minutes at Ibrox.

It's becoming a bit ragged from Rangers and we seem destined for 30 extra minutes.

We are into three minutes of stoppage time.

Can anyone find a late goal to avoid extra-time?

Rangers are upping the tempo, desperately determined to avoid extra-time.

They do often seem to find a late goal, although it was Saints who equalised in stoppage time in their midweek league encounter.

It looks like Scott Wright is going to score for the second game in a row against Saints as the former Aberdeen forward plays a neat one-two with Kemar Roofe, but his poked effort is parried by goalkeeper Zander Clark.

Michael O'Hallaran is a threat for his pace up front and breaks almost clear behind the Rangers defence.

He looks to have delayed his shot too long but then finds it blocked on the line off the legs of goalkeeper Allan McGregor for a corner.

That's Alfredo Morelos' last involvement.

The Colombia international is fuming as he takes his seat after being replaced with Kemar Roofe.

Alfredo Morelos, having already been denied by a post, must wonder what he needs to do to score.

The Colombian is found by a Ryan Kent cross to the back post and his header is cleared off the line off the foot of goalkeeper Zander Clark.

St Johnstone are still a threat in this game and Liam Craig's corner finds the head of Liam Gordon.

However, the defender's effort is easy for goalkeeper Allan McGregor.

A few nervous moments for the home side now though.

Is the stage set for former Rangers striker Michael O'Halloran to come back to haunt his former side?

He is sent on to replace the tiring Stevie May, who has put in a big shift up front for the visitors.

Rangers continue to press and Borna Barisic curls in a powerful, curling free-kick, but goalkeeper Zander Clark is well placed to push it wide for a corner.