The Brazilian was shown a straight red card for kicking out at David Luiz after Juan Mata had scored the only goal of the game in the 87th minute, and while Ferguson lamented his player's reaction to provocation from Luiz, the Scot did not believe Rafael deserved to be dismissed.
 
"It was the elbow, that's what happens, the player retaliates and pays the penalty," Ferguson told Sky Sports.
 
"It was clear Luiz elbowed him twice actually, it was rash what he's done, he's a young lad but retaliation never works.
 
"I wouldn't say it was violent conduct. I don’t think the referee's seen it at all, he's gone with the fact that Luiz has rolled four or five times.
 
"I can't make any excuses for our players in terms of the performance, certainly a lot of the decisions went against us, they were surrounding the referee all day.
 
"I don’t think it was a foul (on Wayne Rooney in the build-up to Mata's goal) but we wouldn't have got anything from the referee anyway. It was a bit of a lucky goal, it deflected off Phil Jones so there was a wee bit of luck with that."
 
Ferguson conceded that the champions had not played well enough to claim victory against the UEFA Europa League finalists after a largely sterile display at Old Trafford.
 
"I think obviously we had the foot off the pedal in a big way," the 71-year-old commented.
 
"Chelsea deserved to win, it was controversial but it always is with Chelsea. We can't complain, we didn't play well enough. It's difficult to say why."