Both Chelsea manager Maurizio Sarri and Tottenham Hotspur boss Mauricio Pochettino criticised VAR after the system played its part in deciding the outcome of Tuesday's Carabao Cup semi-final first leg between the two sides at Wembley.
Spurs edged the contest 1-0 thanks to Harry Kane's 26th-minute penalty.
There was no doubt the Englishman was fouled in the box by Blues goalkeeper Kepa Arrizabalaga.
However, referee Michael Oliver consulted VAR to check Kane was onside when he was put beyond the defence by Toby Alderweireld's long ball—the assistant initially flagged offside.
The official system adjudged he was onside so the penalty was awarded and Kane converted.