Fans have only just discovered incredible hidden technology in Champions League matches that will blow your mind

Fans are only just discovering that there is an incredible hidden piece of technology that is in use for Champions League matches.

The current season of the Champions League is well underway, with teams having played four group matches each.

Of those 36 teams competing, only Liverpool have a 100 per cent record, with 12 points from their first four games.

As is always the case, VAR has had to play an active role in decisions across many matches - perhaps none more so than Wednesday when it intervened to give a penalty against Aston Villa after Tyrone Mings inadvertently picked up the ball from Emiliano Martinez's goal kick.

But while VAR has now been in place for several seasons, and semi-automated offside decisions are now becoming the norm, there is another piece of technology in use that fans are only just finding out about - and it's all to do with what you see on your screens.

During matches, it is mandatory for every Champions League club to have LED advertising boards installed across the four corners of the stadium, with adverts automatically changing at regular intervals.

And while you may not take too much notice of the actual sponsors on the boards - although a lot of the brands are instantly recognisable - TV officials actually have control over which adverts get broadcast around the world.

Live TNT Sports footage showed the Qatar Airways logo on the LED board

After Viktor Gyokeres scored a penalty for Sporting Lisbon in their 4-1 win over Manchester City on Tuesday, the television camera angle showed a Qatar Airways advertisement behind Ederson's goal.

However, when a replay of the goal was shown, there was an image of the FedEx logo instead on the same board - meaning the board was different for those in the stadium compared to people watching on TV.

Viktor Gyokeres celebrates with the FedEx logo clearly visible in the background - Getty

The reason, The Sun report, is to comply to local advertising regulations as well as showcasing brands on the global feed - using a piece of technology known as a virtual board replacement.

"This approach ensures compliance with local advertising regulations while maintaining visibility sponsors on the global broadcast feed."

It is, however, only used in selected markets - though it is clear that the UK market is definitely one of them.