VAR: Manchester United boss Jose Mourinho says system must be perfect

Manchester United boss Jose Mourinho says the video assistant referee (VAR) system must be improved after his side had a goal ruled out in their 2-0 FA Cup fifth-round win at Huddersfield.

The VAR disallowed a Juan Mata goal for offside, but it did not affect the outcome after Romelu Lukaku'a goals.

"I'm familiar with what VAR is bringing that's good and bad," said Mourinho.

"I think it's an experimental period. They have to get rid of the bad and make it perfect."

Mata put the ball in the net just before half-time when he peeled away from the Huddersfield defence to meet Ashley Young's neat pass, rounded goalkeeper Jonas Lossl and slotted in from a tight angle.

The midfielder was celebrating as referee Kevin Friend had his finger to his earpiece before the offside call was made by VAR.

"I did what I had to do which was to score and celebrated," Mata said. "Then after I saw the referee speaking to someone and you look silly when the goal is denied.

"I'm up for VAR and I think it is good for football especially to make important decisions and make it a little bit fairer, but it seems like today it was not a very clear decision against us and me.

"The good thing was [the goal] was not needed because we won anyway but I think we all wished it was quicker. I celebrated and it didn't count."

• Match report: Lukaku scores twice as Man Utd beat Huddersfield

• Man Utd to face Brighton in last eight

• Watch all of the latest FA Cup highlights and reaction here

Unlike Mourinho, Huddersfield boss David Wagner does not think VAR is good for football.

"Yes, the decision went in our favour but this VAR for me kills the emotion of the game," he said.

"This is why I don't like it - but I am not the person who makes the decision."

Major VAR moments in the FA Cup this season

8 January - Brighton's win over Crystal Palace is the first English club game with VAR available, but it was not used to overturn a decision

16 January - Leicester's Kelechi Iheanacho has a goal disallowed in the win over Fleetwood for offside - but it is then awarded after VAR consultation

17 January - Chelsea's Willian is booked for diving against Norwich, when it appeared he was fouled in the box, but the VAR did not launch a review

27 January - In Liverpool v West Brom, the referee and VAR consulted to rule out an Albion goal, give Liverpool a penalty and delay awarding the Baggies their winner

What is VAR and why is it being used?

The VAR system - which is being used in some Fifa tournaments, as well as Serie A and the Bundesliga, has been trialled in certain FA Cup games this season involving Premier League clubs.

It can only be used at stadiums where there is a direct link back to the Premier League studios west of London - where the VAR has access to between 12 and 15 camera angles, including four cameras in each goal.

If the VAR thinks there is a clear and obvious error, he will tell the referee, who can either change his decision or view the incident again on a monitor at the side of the pitch.

Where a VAR review is used, it will normally be triggered during stoppages in play and limited to four types of match-changing incidents:

• Goals

• Penalties

• Straight red cards

• Mistaken identity

What did the BBC pundits think?

Former Manchester United assistant boss Steve McClaren on BBC Radio 5 live:

"We saw it once and our judgement was that Mata was onside. I'm satisfied after seeing it again, it's offside.

"It was close. There are teething problems with VAR - but if it takes 20 minutes, that's how long it should take.

"If it proves that it's the right decision, then it's right to have VAR."

Former Everton midfielder Leon Osman on Match of the Day:

"It is close but they do get the decision right. If you are going to use it you have to make sure you get the decision right.

"It is difficult for the linesman to see. No-one would give the linesman any grief for not giving offside.

"But VAR slows the game down. It takes momentum from the crowd and sometimes that is not a good thing.

Former England defender Matthew Upson on the lines shown on BT Sport as a guide to whether Mata was offside:

"It is a problem that will and has to be tidied up. We have heard that these lines weren't used to make the decision but that is what we saw. As the public watching, If you saw those lines it does not fill you with confidence in VAR.

"For me, my biggest fear with VAR is that the game isn't perfect. The game isn't played in a perfect environment. There are so many moving parts. Even when we freeze situations like this, you still have an imperfection as to whether you can call it offside. It brings a negative part to the game.

"Some decisions are clearer. They have lines and are quick. This is a difficult one to use VAR on."

What you said using #bbcfacup or by texting 81111

David Bushell: Didn't know VAR stood for complete and utter guesswork.

Adam: I don't think I can watch the FA Cup on the basis that VAR causes my blood pressure to go through the roof.

Gorg Ed Hidar: Another failure for VAR - Mata was level (i.e. onside) and the blue lines on the pitch didn't even look like they were drawn straight. Robbery.

Chris: The linesman kept his flag down so VAR has been used to change a correct decision to an incorrect decision. Bizarre!

Joe Dempsey: I thought the whole point of this technology was to get the decision 100% right, 100% of the time? That was a clear goal.