Vieira was left fuming at the refereeing for Chelsea's 2-1 win.
In quotes reported by ESPN Soccernet, he said: "We can't understand how a Slovenian referee (Damir Skomina) was in charge of this match and we will explain our position to the Portuguese federation.
"I don't know whether the federation is capable of doing anything. Surely everyone saw what happened here. It is evident that this is a business and that there was no desire to see Benfica go through. Refereeing has reached a scandalous point."