What is semi-automated offside technology and how will it work in the Champions League and at the World Cup?

Fans tuning into the opening round of Champions League action for 2022/23 might well spot something they’ve never seen before.

Semi-automated offside technology (SAOT) will be used in European football’s showpiece tournament this season for the first time, as well as at the World Cup at the end of the year in Qatar.

It was used in the UEFA Super Cup between Real Madrid and Eintracht Frankfurt last month and will quickly become a regular feature of the elite European game.

But what is it, and how does it work?

‘Enhancing the flow of the game’

SAOT enables video assistant referee (VAR) teams to make a call on offside decisions quickly and more accurately.

UEFA chief refereeing officer Roberto Rosetti vowed that it will ‘enhance the flow of the game and the consistency of the decisions.’

That will be done by having specialised cameras that track up to 29 different body parts on each player, and 12 cameras underneath the roof of the stadium that track the ball.

The position of each player is tracked 50 times per second to work out their exact position on the pitch at any given moment.

How will it be used in a game?

While tracking ball and player data, the technology will produce an automated offside alert to the video match officials if an attacker receives the ball in an offside position.

The video match officials will then validate the proposed SAOT decision by checking manually before they inform the on-field referee.

This should happen ‘within a few seconds’, according to FIFA, leading to quicker offside calls.

Once the on-field referee has confirmed the decision, the data points used for the decision will generate a 3D animation that shows the position of the players’ limbs at the exact moment the ball was played.

This animation will be displayed on the big screens inside stadiums, and shared with broadcasters, so that fans can be kept in the loop.

What if the video match official doesn’t agree?

The video match official can manually select the kick point or draw the offside line if they don’t agree with those set automatically by the SAOT.