The flashpoint in the draw with Dundee United raised eyebrows of pundits and former officials

Bobby Madden has mapped out the criteria that would have seen VAR intervene after Colby Donovan's heavy challenge against Dundee United

The former SFA referee has had his say after the tackle on Zac Sapsford with the Glasgow giants trailing 2-1 at Celtic Park, with referee Steven McLean issuing a yellow card for the tackle by the right-back.

Chris Graham and the VAR team would check the flashpoint, but the off-field team would ultimately back up the man in the middle over the booking.

Liam Scales would go on to level the game for Celtic and help keep the Hoops four points clear at the top of the Scottish Premiership - but comparisons would be drawn to the red card issued to St Johnstone's Kai Fotheringham against Rangers last weekend.

The Saints wide man was pulled up by the VAR team at Ibrox for a similar challenge on Nico Raskin at Ibrox - which saw referee Chris Graham sent to the monitor, and a red card issued.

But Madden insists that neither should have been been considered a red card and VAR should not have stepped in, as he laid out the IFAB guidelines.

Talking to his Instagram page ahead of Celtic's clash with Falkirk this weekend, the former whistler said: "A much discussed decision from the match between Celtic and Dundee United on Wednesday night, which is absolutely clear in line with the laws of the game and current criteria.

"If you look at the challenge, the Celtic player comes in and clearly plays the ball before he makes contact with the opponent.

"So, let's look at what the law says. So, obviously this is a genuine attempt for the ball so it's not violent conduct, so we need to determine if this is a yellow card offence for reckless, which is showing a disregard for the opponent, or is it serious foul play and endangering an opponent.

"So, when considering a red card offence for endangering an opponent we need to consider does he play the ball, or is there an opportunity to play the ball? Is there speed, intensity or is there any malice?

"So, if we consider that criteria there is speed in the challenge, there is intensity. Is there an opportunity to play the ball? Of course, as the defender plays the ball.

"Is there any malice? There is no extension of the leg even after the challenge, even though there is some contact.

"When we are considering serious foul play, only last weekend Kai Fotheringham was sent off against Rangers and I was quite clear that it is not a red card even - given that point of contact.

"What we need to look at here [during Celtic vs Dundee United] is consistency of decision-making. If you look at this challenge made by Donovan it does not meet the threshold for a red card. Yes, there is speed and intensity but there is not significant enough contact on the opponent to be considered to be endangering the safety of that opponent.

"Red card offences should be absolutely clear. In this situation the referee was correct and the VAR was correct not to intervene."