West Brom 1 Manchester United 0: Louis van Gaal questions Mike Dean's judgement in sending off Juan Mata

Mata received two yellow cards in two minutes to pick up the first red card of his professional career

Juan Mata complains after Mike Dean shows him a red card (Getty Images)

Louis van Gaal accused referee Mike Dean of being too quick to dismiss Juan Mata after the referee sent off the Manchester United midfielder for two yellow cards in the space of two minutes as his team’s Champions League hopes suffered a damaging blow at The Hawthorns in defeat by West Bromwich Albion.

United were forced to play with ten men for 64 minutes following Mata’s first-half dismissal – for failing to retreat at a free-kick and then fouling Darren Fletcher – before going down to a 1-0 defeat.

But despite Mata’s recklessness with the challenge on Fletcher, Van Gaal refused to condemn the Spaniard.

"What can I say when you send off a player like Mata?” Van Gaal said. “I have asked him if it's his first red card and he said yes.

“When you give the first and second yellow within minutes, you can do it according the rules, but I think the referee has to know the person doing it.

“I don't think Mata has ever had bad tackles and something like that. Most referees show that [discretion].

"You know the first one is a stupid yellow card and then you have to be aware the referee can give a second yellow card.

“A referee has to decide within one second but when you know the player, Mata never hurts a player.”

Juan Mata looks on after being sent-off against West Brom (Getty Images)

Tony Pulis, whose team ended a 32-year wait for an Albion home league win against United, insisted that his players had to fight for the victory, despite Mata’s red card forcing the visitors to play with ten men for over an hour.

"Them going down to ten men affected the game,” Pulis said. “But we watched Liverpool go down to ten before this game [against Crystal Palace] and they won 2-1.

“You're never comfortable against top teams with pace up front and they have pace, but once we got the goal we kind of settled down.”

West Brom midfielder Darren Fletcher claimed Mata, his former United team-mate, could have no complaints about Dean’s decision to brandish two yellow cards.

"It was the referees decision,” Fletcher said. “I tried to take a quick free-kick and got blocked and then tried to start a counter attack and got tripped.

"I thought we looked flat when they went to ten, but the advantage of 11 v 10 seemed to get us through in the end.”

Juan Mata walks past Louis van Gaal after being sent-off (Reuters)

Despite refusing to blame Mata, Van Gaal admitted that the defeat has left United battling to climb into the top four.

“It is a bad moment for us,” Van Gaal said. "The loss is a big blow because it was not necessary. When you see the first half it was not necessary I think."

Defeat now leaves United needing to close a three-point gap on Manchester City – their next league opponents on March 20 – to sustain realistic hopes of Champions League qualification, with midfielder Michael Carrick admitting that the team must now launch another winning run.

"It's a setback,” Carrick said. “We wanted to carry on the form and results we have shown of late, so it's very disappointing. Losing a man like we did makes it even more difficult.

“But the top is not out of sight. We just need to get back to winning ways, but that’s easy to say. We have big cup games coming up and we need to be ready to them."