The Red Devils eased to a 4-1 victory at Pride Park in the fifth round of the FA Cup.
United claimed the comfortable success courtesy of goals from Nani, Darron Gibson, Cristiano Ronaldo and Danny Welbeck.
Ferguson was delighted at the comprehensive nature of his side's performance and was particularly pleased with those who currently sit on the fringes of his first-team squad.
"We applied ourselves very well," the Scottish coach told MUTV.
"The players had a good attitude, they all wanted to play and that made the pace of the game really quick. I was very pleased.
"Nani's goal was marvellous and came at a good time for us, but he's capable of doing that.
"Danny is a natural finisher and his goals to games ratio is very good. He's only 18 but he's improving all the time."
The result could have been even more commanding were it not for a debateable first-half decision to rule out a Ronaldo effort.
ConfusionThe Portuguese superstar saw a composed finish chalked off by a very late offside flag, with Ferguson left aghast by the reasons given by the match officials for the considerable delay.
"The linesman created his own confusion because he went so long, until after the goal had been scored, to say it was offside," said Ferguson.
"He said he was waiting to find out whether Ryan (Giggs) had touched it. Nevertheless, Ronaldo was still in an offside position.
"I have no complaints about the actual decision. It was the fact he waited so long. I did not understand the explanation."
Ferguson was, however, more complimentary towards 21-year-old Gibson, with the youngster having played his way into his manager's thoughts for the Carling Cup final against Tottenham on 1st March.
"Darron did really well," said Ferguson.
"He has got into the Carling Cup final team with that performance.
"He has played in every round, so he deserves it."