A third spot-kick for the home side! A ball in behind for Jonah Ayunga sets him through on goal, and Liam Scales and Ross McCrorie seem to both bring him down.

Here come the cavalry...

Three changes for Celtic with Sead Haksabanovic, Liel Abada and Jota coming on up front in place of James Forrest, Matt O'Riley and Daizen Meada.

Triple substitution for the Saints too, with Nicky Clark, Daniel Phillips and Melker Hallberg making way for Alex Mitchell, Cammy MacPherson and Connor McLennan.

Aberdeen substitute Ryan Duncan fizzes a shot wide.

Up the other end, Ryan Strain skins a few players but dinks his effort over the bar.

United boss Liam Fox speaks to BBC Sportsound: "There's always that concern [about rustiness]. We were disappointed with the game being off last week. We did a lot of work over the break so we'll hopefully see that come to fruition over the next couple of months.

"Excited. We're looking forward to it but it's a tough task against a very tough side. We've got big games coming up and it's a real carrot for the boys to know if they win they'll come off the bottom.

"I watched Hearts last week, they performed well and have quality in all aspects of the pitch. We're at home, we had a good result in our last home game and were looking to a similar performance to that."

Jane Lewis
BBC Sport Scotland at Celtic Park

What an afternoon for Reo Hatate! The midfielder answered an SOS call to play at right-back for Celtic and not only has he been untroubled playing out of position, he's scored two goals. Fantastic stuff from Celtic, St Johnstone have no answer.

The Buddies have their second spot-kick of the afternoon...

A mix up at the back and goalkeeper Kelle Roos is late off his line, wiping out Curtis Main.

Pat Bonner
Former Celtic goalkeeper on BBC Sportsound

It was the slickness of the move - the one-touch passing was really sharp from Celtic.

Aberdeen have made two changes at the break. Jack MacKenzie and Ryan Duncan are on. Duk and Leighton Clarkson are off.

St Mirren have also brought on Greg Kiltie, Ethan Erhahon, who was on a yellow, is off.

Tyrone Smith
BBC Scotland at Tannadice

These two served up 18 goals in four games last season, and earlier this term the capital club prevailed in a 4-1 victory over the Tangerines.

The postponement of last weekend’s scheduled trip to Livingston means United haven’t played since the middle of November.

Liam Fox will be hoping his side can thaw quickly after their period of cold storage as they look for the win which would lift them off the bottom of the Premiership.

As for Hearts, it is no coincidence that their upturn in form has coincided with the end of their involvement in European competition and, more importantly, the gradual easing of their injury list.

Robbie Neilson’s side now have third place very much in their sights.

We're up and running again at Celtic Park.

The game in Paisley will soon resume too.

And now VAR is working at Easter Road.

Someone must have switched it off and on again...

Hibs boss Lee Johnson makes one change to the side that lost 3-2 to Rangers last time out, as Lewis Stevenson comes in for Marijan Cabraja on the left-hand side of defence.

It was a back four against Rangers with Ryan Porteous starting in midfield, but Johnson hinted that it will be a back five this afternoon.

For Livingston, their first choice midfield returns having started on the bench against Celtic on Wednesday evening.

Jason Holt, Andrew Shinnie and Scott Pittman all start, with Sean Kelly, Stephane Omeonga and James Penrice dropping to the bench.

The other change from Davie Martindale sees Dylan Bahamboula replace Jackson Longridge.

Image source, SNS

Aziz Behich returns to Tannadice, looking to carry on his fantastic World Cup form. The left-back was one of the surprises of the tournament with Australia, after struggling to impress in the first half of the season with United.

Arnaud Djoum also comes into the starting eleven against his former club. The Cameroon international left Hearts in 2019 following the Scottish Cup final defeat to Celtic but he is warmly remembered for his time in Gorgie.

He's not the only connection. Liam Smith and Tony Watt also had spells at Tynecastle - as did boss Liam Fox, who was part of the coaching staff for three years.

Image source, SNS

Robbie Neilson was clearly happy enough with his Hearts side that dispatched Kilmarnock 3-1 last weekend, as he's kept the same eleven.

One assumes he'll stick with the formation, too. That would mean a back three of Halkett, Kingsley and Cochrane, with Halliday and Michael Smith the wing backs. Josh Ginnelly would play up front next to Lawrence Shankland - who returns to his former club.

Kye Rowles returns from suspension but only makes the bench.

Image source, SNS

What happens if there are gremlins at play?

The SFA has put extra provisions in place to ensure there is a back up. Infrastructure and networking has been installed at every ground just for VAR, while there's also a back-up monitor, and a back-up phone if communication is lost with the on-field referee.

If VAR ever does become non-operational and is not likely to come back, then, as per the Laws of the Game, we just continue without it. Like the good old days of September...

Dundee United: Birighitti, Freeman, Smith, McMann, Djoum, Edwards, Behich, Levitt, Harkes, Middleton, Fletcher,

Substitutes: Eriksson, Mulgrew, Graham, Niskanen, Sibbald, Meekison, Sadat, Watt, MacLeod.

Hearts: Gordon, Halkett, Kingsley, Cochrane, M Smith, Devlin, Halliday, Snodgrass, McKay, Ginnelly, Shankland.

Substitutes: Clark, Grant, Kiomourtzoglou, Atkinson, Rowles, Forrest, Sibbick, Henderson, C Smith.

Hibernian: Marshall, Cadden, Porteous, Bushiri, Hanlon, Stevenson, Campbell, Magennis, Newell, Youan, Nisbet.

Substitutes: Schofield, Cabraja, Kenneh, Henderson, Mitchell, Melkerson, McKirdy, Fish, McGeady.

Livingston: Konovalov, Devlin, Obileye, Fitzwater, Montano, Holt, Shinnie, Stephen Kelly, Pittman, Bahamboula, Anderson.

Substitutes: Hamilton, Boyes, Cancar, Penrice, Longridge, Sean Kelly, Omeonga, Goncalves.