Arsenal celebrated taking the lead against Brentford on Saturday night thanks to Kieran Tierney - but their joy was short-lived as the new semi-automated offside system finally adopted by the Premier League this week made its presence felt at the Emirates Stadium. Tierney looked rather sheepish as he found the net following Ethan Nwaneri's delicious cross, a sign that the Scotland international knew he was perhaps in an offside position. However, the on-field officials initially allowed the effort to stand. However, when VAR got involved, making use of the newly-adopted technology, Tierney's effort was swiftly cancelled out. Arsenal fans made their feelings on the decision known, jeering as it was ruled out - despite it being correct. A statement from the Premier League Match Centre on social media declared: "VAR checked the referee’s call of goal – and established that Tierney was in an offside position and recommended that the goal was disallowed." The Premier League announced in the build up to the weekend's fixtures that it would finally be making the move to using semi-automated offsides. The technology, which was originally intended to be introduced after one of the autumn international breaks in October or November, eventually made its debut in English football in seven of the eight fifth-round FA Cup ties at the start of March. Following additional non-live testing in the Premier League, SAOT, using virtual offside lines and graphics along with optical player tracking for those watching at home or in a stadium, has now made its way to the top division in England. Using 30 cameras around a stadium, the technology is set to be used in close offside decisions and, like VAR, will help confirm or suggest a change to the on-field decision made by the referee. The Premier League has worked with Professional Game Match Officials Ltd and Genius Sports to develop the technology. Speaking in February, Premier League chief football officer Tony Scholes said the system was “the most accurate and the most future-proof” available. Join our new WhatsApp communityand receive your daily dose of Mirror Football content. We also treat our community members to special offers, promotions, and adverts from us and our partners. If you don't like our community, you can check out any time you like. If you're curious, you can read our Privacy Notice.