Fabio Maresca became the first referee in Serie A to use VAR technology to award a penalty on Saturday, only to see veteran Juventus goalkeeper Gianluigi Buffon rescue the hosts.
Maresca initially waved play on after Cagliari striker Duje Cop came down under a challenge from Brazilian winger Alex Sandro in the 37th minute in Turin.
But doubts persisted, and Maresca opted to consult the VAR before then pointing to the penalty spot -- registering the first time a penalty has been awarded in Serie A after consultation with the video assistant referee.
Much to Juve's relief, Buffon guessed right and blocked Diego Farias's spot-kick, leaving the six-time defending champions 2-0 up at half-time after goals from Mario Mandzukic and Paulo Dybala.
The International Football Association Board (IFAB), which governs the laws of the game, authorised VAR to be used on an experimental basis in March 2016.
It can only be used to decide whether or not to award a goal or a penalty, for straight red cards and in cases of mistaken player identity.
FIFA president Gianni Infantino said in April that VAR technology would be used at the 2018 World Cup in Russia after "very positive feedback" following its use at the Confederations Cup.
He said: "Video assistant refereeing is the future of modern football."