Former Manchester United full-back Gary Neville admitted Nani's sending-off against Real Madrid left Old Trafford more stunned than he has ever seen it.
The 38-year-old claimed the winger did not deserve the red card shown him by Turkish referee Cuneyt Cakir for a foot-up challenge on Alvaro Arbeloa in the Red Devils' 2-1 loss to Real Madrid, which sealed a 3-2 aggregate defeat.
He Tweeted: "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!"
Neville felt that if Nani deserved red then so did Madrid goalkeeper Diego Lopez for making contact with Nemanja Vidic when the United defender got his head to a corner ahead of the keeper.
"The Madrid keeper on Vidic looked a similar type of incident," Neville added.
"Anyway it won't be the first time or last! Just ruined a fascinating match and didn't feel right to Utd or Madrid people in the stadium!"
Another former United captain, Roy Keane, felt Nani's red card was merited, though.
Keane said on ITV: "I think the referee has actually made the right call. Everyone's upset about it and it's slightly unlucky, but it's dangerous play. Whether he meant it or not is irrelevant.
"It's dangerous play - it's a red card. 'You have to be aware of other players on the pitch. Does he think he's going to have 20 yards to himself?
"Whether it's [a brave decision] or not, it's the right decision. Whether he meant it or not doesn't matter.
"Nani's a quick boy to go down anyway. He's not the bravest player on the planet."
Keane insisted the referee had carefully considered his decision.
He added: "It doesn't matter if he knows there's somebody there or not, it's irrelevant. I don't think the referee actually made the decision because he waited a couple of minutes while the player was getting treatment.
"I think it might have been the assistant that made the decision, and I actually think he's made the right call.
"We always say referees are very quick to make decisions - he waited a couple of minutes.
"Any time I was sent off in my career I always thought, 'did I give the referee chance to send me off?' And if the answer is yes, then it's out of your hands."
Lou Macari, the former United midfielder, branded Cakir's performance "rubbish".
"I thought it was a strange decision - a referee from Turkey who we hadn't heard of. He had no great reputation of being one of the top referees," he told BBC Radio Five.
When it was pointed out that Cakir was well regarded in Europe, he said: "He's still rubbish.
"You don't have referees like that for these big games. The referee's assessor was there last night and he's a proper referee from the past, (Pierluigi) Collina.
"I am sure he looked at the decision and thought, 'he's got it wrong'.
"I couldn't believe it when he pulled out the red card - it was simply a wrong decision."
Former Manchester United captain Bryan Robson was also critical of Cakir's decision.
He said on Sky Sports News: "I think the only person in the stadium who thought it was a sending off was Roy Keane (who was working as a pundit for ITV).
"I'm glad Keane didn't take up refereeing as a profession."