Former Scotland international John Beattie has questioned why referee Craig Joubert ran off the pitch after Australia's 35-34 victory over Scotland.
The South African official gave a controversial penalty for a deliberate knock-on by Josh Strauss, with Bernard Foley sending his kick between the posts to seal victory for the Wallabies.
However, Beattie is mystified as to what made Joubert run straight off the field at Twickenham, immediately after the final whistle.
He told BBC Sport: "I think World Rugby have to tell us why the referee ran off the pitch. Was he being threatened by Scotland players? I don't think so. Was a bottle thrown at him? Well, that's one idiot in the crowd.
"If he ran off because he got the decision wrong, then that is a disgrace.
"We lost the game, but the referee was a numpty. When you're Scotland, it feels as if we're the little nation, and the big guys get the decisions, but I might be wrong."
Australia will now face Argentina for a place in the Rugby World Cup final.
