Chelsea to become first Prem side to trial limb-tracking tech at Club World Cup

FIFA's innovative limb-tracking offside technology has been undergoing vigorous trials for years and it only made its debut in December.

Football's governing body are once again utilising semi-automated VAR during the Club World Cup ahead of its roll out at the World Cup in Qatar.

The upgraded VAR has already disallowed its first-ever goal, chalking off a striker from Al-Jazira striker Alameri Zayed during his side's 4-1 win over AS Pirae of Tahiti.

The semi-automated system will eventually find its way into the Premier League but how much do we know about it? talkSPORT.com takes a look…

What is semi-automated offside?

The new system aims to both reduce the time it takes to make an offside decision while providing greater clarity to supporters around each call.

The AI-based tech uses between 10 and 12 cameras to create three-dimensional models of a player's skeleton to determine whether any part of their body is offside.

"It is based on limb-tracking technology, or as some call it skeletal-tracking technology," Johannes Holzmuller, Football Technology & Innovation director, told FIFA's Living Football show.

"We call it semi-automated offside because it's still, in the end, the VAR who has to validate and confirm the proposed offside line and the proposed kick point that comes out of the software, and then the VAR informs the referee on the pitch about the decision."

How does semi-automated offside work?

The old VAR system relied on regular broadcast cameras from Sky and BT which caused the infamous lines across a 2D image.

Yet these new cameras will record the whole match before generating a virtual replay within seconds to adjudge offsides from any vantage point.

This will allow players, managers and staff to watch a full replay of any incident within seconds from any point or perspective of the pitch or above.

Initial plans have stated that it will be rolled out for use in the Premier League, and all major domestic leagues, by the start of the 2023/24 season.

"It's a camera-based system," Holzmuller added. "We install 10 to 12 cameras inside the stadium underneath the roof.

"These cameras are following the players and tracking up to 29 data points at 50 times per second, and this data is then almost in real time processed and calculated by the software, by Artificial Intelligence, and this is sent automatically to the VAR and the replay operator."