Roy Keane and Jamie Carragher disagree on controversial red card in Man Utd loss to Leeds

The big talking point came in the 56th minute, however, with Martinez dismissed for pulling the hair of Dominic Calvert-Lewin.

Despite protesting his innocence, the 28-year-old was sent down the tunnel - with United unable to get anything from the fixture as a result.

Carrick was left furious at the decision to send off the Argentina international, with the United manager branding it 'one of the worst decisions I've ever seen'.

Keane and Carragher, however, have differing views on the matter.

Keane acknowledged that while it was potentially soft, the fact that Martinez did tug on Calvert-Lewin's hair meant he had to go.

The former United captain said on Sky Sports: "I can see it from both sides and when you class it as violent conduct, it feels really harsh.

"But we've seen other players getting sent off. It is harsh but if that's the laws of the game, then you have to accept it."

Carragher, however, suggested that it was the wrong call.

"He's going for the ball and he's almost grappling. He's trying to grab onto something and he's caught the back of his hair - it could've been his hair or anything," said the ex-Liverpool star.

"He's got him for about half a second.

"We hear from Howard Webb and he says 'what does the game want?'

"I don't think any football fan, manager or player is thinking 'that's a red card'.

"Everybody is looking at that and thinking 'oh come on, that is not a red card, behave yourself'."

The result was a big setback for United.

They've been consistent since Carrick took over from Ruben Amorim in January but, on Monday, they were simply outplayed by their rivals.

United were particularly bad in the first half, with Leeds capitalising to race into a 2-0 lead at the break.

Though the Red Devils did pull one back through Casemiro, they've now missed out on the chance to put more ground between themselves and Aston Villa in the race for Champions League football.

Carragher, explaining United's sluggish start, stated: "Sometimes you don't have good spells in games, other times you do. We know we can be better and do things better.

"We'll look at that. But the way we played second half, and could've got something out of the game in the second half, I'm pleased the way we went into that."

Leeds boss Daniel Farke, meanwhile, was thrilled with his side's display.

"It gives us confidence. A win is always good for that, and for the table," said the German. "But performance-wise we should be on far more than 40 points.

"The reality is we are on 36 points and we need a few more points. Tonight we are three points closer but nothing is achieved yet, we have to stay humble, grounded, hungry and make sure we are ready for the upcoming games to win as many points as possible."