Former Manchester United captain Gary Neville said he had never seen Old Trafford as stunned as it was when Nani was sent off in the Champions League defeat to Real Madrid.
The Portuguese winger was shown a red card by Turkish referee Cuneyt Cakir when he caught Real right-back Alvaro Arbeloa as United, 1-0 up at the time, went on to lose 2-1.
But lifelong United fan Neville, who made 602 appearances for the club and is now part of England manager Roy Hodgson's coaching team, branded the official "poor".
He wrote on Twitter: "Been going to OT since age of 5 and I've never seen the whole ground as in disbelief as they were last night at a decision!
"Nani is a player who regularly tries to control a pass like this over his shoulder and its never a red card! Changed the whole game! Poor ref."
"The crowd actually weren't angry / weren't shouting they were just open mouthed and in shock! Just ruined a fascinating match and didn't feel right to Utd or Madrid people in the stadium!"
United's assistant manager Mike Phelan called Cakir's decision to dismiss Nani "amazing" and said manager Sir Alex Ferguson was "distraught" and "in no fit state" to speak to the official.
However, Neville's former team-mate Roy Keane had insisted that Nani was rightly dismissed, calling it "dangerous play".
Neville also argued that if Real 'keeper Diego Lopez made a comparable challenge on United skipper Nemanja Vidic and escaped unpunished, adding: "The Madrid keeper on Vidic looked a similar type of incident."