CALUM BUTCHER'S wild tackle on Celtic star David Turnbull has been branded a "leg-breaker" with a former ref insisting he should've been sent off.

The Dundee United ace slammed into Turnbull minutes after being subbed on and caught the Celtic midfielder just below the knee with his studs.

Referee Don Robertson flashed a yellow card for the tackle at Tannadice as Celtic ran out 3-0 winners in Dundee.

On Sky Sports News' Ref Watch Dermot Gallagher said Butcher should've been ordered off for the horror challenge.

And the challenge also brought wincing reactions from former England attacker Sue Smith and ex-Liverpool player Stephen Warnock in the studio.

Gallagher explained: "I don't think the referee has got the view we've got, because if he's got this view he will certainly red card.

"It's high, it's straight legged, studs, point of contact, it's everything.

"I mean Sue is wincing just looking at it. I don't need to say any more.

"Sue's reaction alone has told you that's got to be a red card."

Warnock then added his thoughts on the challenge, stating: "That's a leg-breaker. It's horrible."

Kris Boyd had slammed the tackle after the match, saying: “It’s a red card all day long. There’s no doubt about it. He’s high, it’s at speed and he’s in endangering the safety of his opponent.

"David Turnbull was lucky to get away with it. It’s a red card all day. I know I said it the other night but the sooner we get VAR in Scottish football the better because that’s a red card.

“David Turnbull is very lucky that he didn’t get a really, really sore one."