Champions League welcomes semi-automated VAR offside, but what's it all about?

FIFA and UEFA have spent the past three years testing out a new artificial-intelligence-based semi-automated offside technology (SAOT), and now it's ready to be rolled out in the Champions League.

Although SAOT was used by FIFA at the Club World Cup in February, and also by UEFA in the Super Cup between Real Madrid and Eintracht Frankfurt in Helsinki last month, most fans wouldn't even have noticed it was there. You could say that's the perfect outcome, but until we regularly see the new technology is changing offside decisions we're in the dark as to its effectiveness.

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The two governing bodies are very confident. FIFA had already approved its use at the World Cup in Qatar, which kicks off on Nov. 20; then unexpectedly UEFA also announced it would start using SAOT for all matches in the Champions League group stage.

The two systems aren't quite identical, though the overall ethos of using AI to produce the offside result is the same.

«For the good of the game and the good of refereeing, UEFA always wants to use the best technology available,» said Roberto Rosetti, UEFA's chief refereeing officer. «UEFA is always looking for new technological solutions to improve the game and support the work of the referees. And this is what we want from semi-automated offside in the future.»

So the curtain has now been pulled back and we know a lot more about a flagship development for the VAR project. So how will it work, what are the good points and where will fans still be left feeling frustrated?

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Long delays, perceived inaccuracies and a lack of confidence in the system among fans, players and coaches. And that's just for