Peter Pawlett's penalty is saved by St Mirren goalkeeper Vaclav Hladky.

Paul McGinn's effort evades Benjamin Siegrist.

Pavol Safranko's stuttering penalty is saved again by Hladky.

Mihai Popescu sends a fine penalty into the top corner.

Osman Sow sends his spot kick off the face of a post.

Callum Booth's awful penalty is straight at Hladky and the goalkeeper beats away the ball with his feet.

It seems ages ago that Nicky Clark scored from an equally controversial penalty for United and Paul Mullen equalised soon after in the first half.

St Mirren have probably shaded it over the course of the two legs, but now it matters not as we go into the shoot-out.

The kicks are being taken at the St Mirren end of the ground.

The final whistle goes and we face a penalty shoot-out to decide which of these sides will be playing in the Premiership next season.

A chorus of "cheat, cheat" goes up from the home fans, left angry by that controversial red card for Duckens Nazon.

St Mirren, down to 10 men, now look to have settled for penalties.

Two minutes or so of extra time to go.

St Mirren forward Danny Mullen goes into the book for clipping the heels of Paul Watson.

Jim Duffy
BBC Sportsound summariser

Another moment of controversy. Duckens Nazon goes up to challenge Mark Connolly and receives a straight red card as the striker's elbow connects with the United defender's face.

It looks completely accidental.

The ball breaks to Duckens Nazon inside the United penalty box, but he blazes his volley wide from 12 yards.

United are not out of this yet as goalkeeper Vaclav Hladky has to rise and clutch the ball under pressure beneath his crossbar from Mark Connolly's looping header.

Duckens Nazon is seeing plenty of the ball, but he chokes his shot wide of the far post as St Mirren continue to press.

Benjamin Siegrist is keeping United in this game and he does well to turn a Jack Baird drive wide as the big defender breaks forward.

United winger Paul McMullen goes down with cramp after crashing into a challenge on Duckens Nazon.

There are no extra subs allowed in this extra time.

Jim Duffy
BBC Sportsound summariser

Cody Cooke's shot takes a deflection wide of the United post, the move started by a clever back-heel by Duckens Nazon.

Neil McCann
Former Scotland and Rangers winger on BBC Sportsound

We are off again and there are only 15 minutes left to avoid a penalty shoot-out to decide who plays in the Premiership next season.

Could it be any more on a knife edge?

It is the United fans who are making most noise as the half-time whistle goes in extra-time.

But it is nail-biting stuff at the Simple Digital Arena.

Image source, SNS

Cody Cooke wins the ball with what looks like a dangerous challenge and the striker takes advantage by powering a shot towards goal.

Fortunately for United, it is straight at goalkeeper Benjamin Siegrist.

Osman Sow has been quiet since coming on for United, but the big striker makes a clever turn only to send his shot weakly wide.

Duckens Nazon looks to have broken clear of Mark Connolly but goes down as the defender's trailing leg kicks out to catch the striker.

No foul is given by referee John Beaton, but it looked like a free-kick and possibly should have been a second yellow card for the United defender.