Juan Mata
Mata's late challenge on Fletcher saw him shown a red card inside 26 minutes.Getty

Manchester United manager Louis van Gaal admits Juan Mata's first yellow card in the defeat to West Brom was "stupid" but questioned Mike Dean's decision to send off the Spaniard.

Mata was shown his second yellow card after a late challenge on former United midfielder Darren Fletcher after just 26 minutes, a pivotal moment in a game his side went into lose 1-0 thanks to a strike from Salomon Rondon.

The result saw United miss the opportunity to move level on points with Manchester City with van Gaal admitting his side have now "lost contact" with the top four.

Mata's second yellow came just three minutes after his first booking for encroachment. Van Gaal said post-match he was so surprised about the sending off he had to ask the Spain international if that was the first time he had ever seen red, suggesting Dean should have taken the player's personality into consideration before giving him his marching orders.

"What can I say when you send off a player like Mata? I have asked him if it's his first red card and he said: 'Yes,'" Van Gaal said, the Guardian report. "When you do that you give the first and second yellow within five minutes. You can do it according to the rules but I think the referee has to know the person doing it. I don't think Mata has ever made bad tackles.

"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."

United managed to register just one shot on target as their four-game winning streak came to an end. Van Gaal admitted his side did not deserve three points at the Hawthorns, but felt they should have returned to Manchester with something.

"The [sending-off] decision was for us the turning point in the match. They scored out of three chances, fantastic, but for us it is a big disappointment. A bad moment and it was, in my opinion, an unnecessary loss. I don't want to say that we deserved to win, but we did not deserve to lose, when you see at the end the chances that WBA created in comparison with us. But now you lose, and lose contact with the first four or five."

United travel to Anfield on Thursday for the first leg of their Europa League last 16 clash with Liverpool before their FA Cup quarter-final showdown at Old Trafford with West Ham United.