Video assistant referees (VAR) will be used for the first time in EFL competition in both legs of the Carabao Cup Semi-Final tie between Chelsea and Arsenal.

VAR will also be in operation at the Carabao Cup final at Wembley on Sunday 25th February.

The use of VAR in the latter stages of the competition follows the EFL’s commitment to support English football’s contribution to the live trial currently taking place across world football – after being introduced in 2016 by the International Football Association Board (IFAB).

Chelsea host Arsenal at Stamford Bridge in the first leg of the Semi-Final on Wednesday 10th January whilst Manchester City face Bristol City in their first-leg tie on Tuesday 9th January.

VAR will NOT be in operation at either of the Manchester City v Bristol City Semi-Final legs.

The role of the VAR is to assist the referee in ONLY four match changing situations:

Goals

Penalty/no penalty decisions

Direct red cards shown or not shown (second yellow cards are not able to be reviewed)

Mistaken identity

The emphasis of the experiment is to focus on clear and obvious errors. In this way, the system aims to minimise any interference with the flow of the game and maximise the advantages of reviewing the video replays. Given the subjective nature of football and a desire to maintain the flow and spectacle of the game, the system is not intended to achieve 100 per cent accuracy in every decision.

The original decision of the referee on the pitch can only be changed if a video review shows a clear and obvious error.

Most of these checks will go unnoticed as they will take place in the background whilst the game is continuing. If a check shows that a clear and obvious error may have taken place a review will then follow. The review process, which can be requested by the referee or recommended by the VAR, takes two forms.

Firstly, the VAR can inform the referee that there is a factual error on a clear situation which does not require the referee to review the video. For example, the player who scored a goal was an in an offside position. You will then see the referee making the ‘TV screen’ signal and he can then change the original decision, disallowing the goal and penalising the offside offence.

In situations that are less clear the VAR will advise the referee to look at the video. This is called an On-Field Review. You will see the referee move to the side of the pitch to review the footage on a monitor before making the final decision. Following a review, the referee will make a ‘TV screen’ signal and communicate the final decision. This may either confirm or change the original decision.

Usually, theses reviews will take place during a stoppage in play and the referee will hold up the game until the review is completed. Occasionally, the referee may choose to stop the game to consider a review. This will only happen when play is in a ‘neutral’ area, typically in midfield.

IFAB will continue to monitor the system and the way it has impacted on the game in the many competitions who are participating in the experiment, before deciding whether to amend the Laws of the Game to include Video Assistant Referees.

The second legs of the Carabao Cup Semi-Finals take place a fortnight later, with Bristol City welcoming Manchester City to Ashton Gate on Tuesday 23rd January and Arsenal hosting Chelsea at the Emirates on Wednesday 24th January.

All four Semi-Final matches will be broadcast live on Sky.