How Offside Lines Work on VAR Amid Liverpool vs. Tottenham Controversy

• Luis Diaz's goal for Liverpool was denied by match officials during their clash with Tottenham
• Miscommunication between the VAR and the centre referee saw the goal ruled out for offside
• Sports Brief looks at how the offside lines work after a controversial moment involving the VAR

The Video Assisted Referee (VAR) was at the centre of controversy once again on September 30 after a goal was ruled out for offside - despite the player actually being onside.

On a night marred by contentious decisions, Liverpool's Luis Diaz saw his effort thwarted by technology intended to assist the on-field referees in their decision-making.

Instead, the Colombian's goal was incorrectly ruled out, with Spurs going on to record a 2-1 win over the Reds.

This was yet another decision which is turning opinion against the VAR, following numerous other calls including one against Alejandro Garnacho almost a full month earlier.

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The Argentine was deemed offside by the tiniest of margins, rendering his 88th-minute strike useless. Arsenal went on to record two goals in stoppage time to condemn Manchester United to defeat.

Red Devils coach, Erik ten Hag commented at the time, per TalkSport:

"Many decisions went against us. I think Garnacho was onside, [Rasmus] Hojlund was fouled in the area and there was a clear and obvious foul on [Johnny] Evans for [Declan] Rice’s goal."

From the naked eye, the re-instated Gabriel Magalhaes appeared to play Garnacho onside as Casemiro threaded the pass through for Man United.

However, after the blue and black lines were drawn, fans were handed the dreaded red line and as former referee, Mike Dean said at the time:

"Technology can't put lines in the wrong place - that was offside."

How exactly does this technology work? Many have asked this question, considering the controversy surrounding the VAR and the decisions which have been wrong - or marginal, at the least.

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How the VAR offside lines are drawn

According to the Premier League, the officials use the hawk-eye’s virtual offside line technology to arrive at decisions. This technology is broken down into the gridline and the crosshair.

The former is straightforward, with a line being drawn on the last defender. Any opposing player who is over the line headed towards the goal is deemed offside.

But at times, the gridline fails to outrightly differentiate whether the attacking player is over the line or in a perfect and legal position - enter the crosshair.

Two one-pixel lines are drawn for the attacker and the defender. The lines are positioned on the parts of the player's body that can be used to score goals. The body parts that are off the ground are shown by 3D virtual lines.

The attacking and defending lines are done manually before the VAR takes over and determines which line overlaps the other.

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"The positioning of the crosshair is manual, with a line one-pixel wide, so that the exact position of the offside line and the relevant body part can be accurately identified by the VAR."

Thicker lines were introduced at the start of this season, where the attacker was given the benefit of the doubt to eliminate the marginal of calls where perhaps only the toe was in an offside position.

The Premier League uses at least five calibrated cameras to determine the positions of the players and find the perfect angle to arrive at the correct decisions.

As far as such decisions go: today it will be given, tomorrow it will be rejected. What's for certain, though, is that VAR drama is here with us to stay. Brace yourself, if you hadn't, for more controversial decisions.

All VAR blunders since last season

Sports Brief also reported on all the VAR errors made in the Premier League as refereeing body, PGMOL owned up to a 'human error' after the Liverpool vs. Tottenham game.

This calendar year alone has seen the body own up to seven mistakes - a grim statistic given the technology was working but let down by those in charge of interpretation.