Albion's FA Cup showdown against bitter rivals Crystal Palace could be decided not at the Amex but at the Premier League's headquarters near Heathrow.

Monday night's third round tie will be the first competitive match in England to use Video Assistant Referee technology.

How does it work, what incidents are covered and who are the key officals?

What is Video Assistant Referee (VAR) technology?

The match referee is supported by a VAR, watching the game on television monitors. He in turn has an assistant to help the match referee with key incidents.

Who are the officials for the Palace tie?

Andre Marriner is the match referee, Neil Swarbrick the VAR and Peter Kirkup the additional video referee.

Where will Swarbrick and Kirkup be situated?

At the Premier League's match centre in Stockley Park, near Heathrow.

What type of incidents are covered?

Only the awarding of goals, penalty decisions, straight red cards and mistaken identity.

Has Marriner taken charge of Albion before this season?

Marriner was the ref for the 0-0 Premier League draw against Palace at the Amex in November and, prior to that, the 1-0 home win over Newcastle in September when Tomer Hemed initially escaped punishment but was retrospectively suspended by the FA for treading on DeAndre Yedlin.

What about Swarbrick?

He was the ref for Albion's 1-0 defeat by Manchester United at Old Trafford in November, when cameras picked up Romelu Lukaku kicking out at Gaetan Bong from the corner which led to United's winner. The Belgian striker escaped sanction.

The Hemed and Lukaku incidents would not have been applicable to VAR.

What about Hemed's goal against Newcastle?

Rafa Benitez complained about illegal blocking when Pascal Gross's free-kick was headed back by Dale Stephens for Hemed to score. That could have been subject to VAR.

So how will it work if something similar happened in the Palace game?

Match ref Marriner (below) can ask VAR Swarbrick for footage to be viewed. Swarbrick can also inform Marriner if he thinks he has made a mistake.

The Argus: A TV monitor will be in place close to the Amex pitch for Marriner so that he can review footage.

The pair will be in permanent contact via the usual headsets.

Will reviews be shown on the big screen, cricket-style?


How well prepared are Marriner and Swarbrick?

Both are on the Select Group of referees for Premier League games (Kirkup is on the Select Group of assistant referees). Refs have been trained for the past 18 months, including a dress rehearsal tournament at St George's Park.

Has VAR already been tested elsewhere?

Ths system has been used, with mixed results, in Germany this season in the Bundesliga and in Italy in Serie A.

What about England?

It has been used in international friendlies, for the first time in England's case against France in June, then also against Germany and Brazil. As well as the FA Cup from the third round onwards, VAR will also be used for both legs of the Carabao Cup semi-final between Chelsea and Arsenal later this month, plus the final at Wembley next month.

What is the plan going forward?

A change to the laws of the game in March to incorporate VAR and full use across the globe, starting with next summer's World Cup in Russia.

Does VAR have the support of everybody?

No. Plenty of people feel human error by referees and subsequent scrutiny of decisions are part of the fabric of the game. They are also worried about interruptions to the flow, although Referees' supremo Mike Riley says: "VAR only intervenes if the referee has made a clear error."

What about the refs themselves?

They are in favour and have encouraged the Premier League to introduce VAR. Marriner is quoted as saying: "We've been crying out for help."