Ferguson confident of response
United have spent the last few days licking their wounds after the shattering disappointed of European failure.
Ferguson is still furious at the manner of his side's defeat, and the controversial decision to send Nani off, which changed the entire course of a game he felt United were comfortable in.
But he knows life goes on. And for the Red Devils that means a meeting with Chelsea, against whom they have already had two titanic contests this season.
"We have a job to do on Sunday and I think we'll do that okay," said Ferguson.
"We've gone through this procedure many times. When you're at a club for a long time there are always damp moments and dark days. In general we recover very well and we'll do that again."
Sunday's quarter-final will be the first time United have faced Chelsea since Ferguson's old rival Rafael Benitez took charge.
The Manchester United manager's irritation with Benitez goes back to the Spaniard's days at Liverpool and that infamous 'It's a fact' rant in 2009, when he claimed Ferguson manipulated referees and received preferential treatment from the Football Association.
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Ferguson has never forgotten the attack and when Benitez turned up at Chelsea following the dismissal of Roberto di Matteo earlier this season, he labelled the former Valencia boss as "very lucky" for being given the chance to take over two Champions League-winning teams, having also replaced Jose Mourinho at Inter Milan.
It has not proved so lucky for Benitez, who has failed to win over sceptical Chelsea support, seen lingering title ambitions quashed, crashed out of the Champions League and is now in a desperate scramble to secure a top four berth.
Benitez has railed against the club's hierarchy for naming him an 'interim manager' and he now accepts there is no chance of getting the job on a full-time basis.
It would normally be a situation Ferguson would approach with relish. Instead, he is taking the softly-softly approach.
"I'm not going to kick anyone when they're lying down," said Ferguson. "It's not my style. My concern is Manchester United. What happens at Chelsea doesn't really affect me. Chelsea have a terrific record in the FA Cup, probably the best of any team in the last decade. It doesn't matter when you play Chelsea or who's in charge, we'll have a hard game."