"In 2013 when Fergie left, he left a depleting squad but one I thought was still good enough to do some damage with a little bit of fresh blood".
However, Guardiola remains wary after Ole Gunnar Solskjaer's men recovered from losing 2-0 at home to Paris Saint-Germain in last season's Champions League last 16 to progress.
"We've shown before we have been down from a home tie and turned it around", Solskjaer said.
"We are still, in our own heads, one of the biggest clubs in the world but it's going to take time".
Defending champion Manchester City will host Fulham, who defeated Premier League side Aston Villa on Saturday.
United won in the league at the Etihad a month ago but on the basis of their performance at Old Trafford - 45 minutes which Solskjaer described as the worst of his reign - they will have to considerably improve if they are to stand a chance of making it to Wembley on March 1. I think everyone knows that we want to win and that the team is fighting. We will give you as much time as possible.
City's midfielders picked their moments to charge forward, and did so with devastating effect.
Silva's goal 17 minutes in set the tone for the visitors as the former Monaco man made a great move atop the box before firing to the far top corner to beat David de Gea.
Guardiola has seen a reaction from his side since that derby defeat at the start of December with eight wins out of nine since - the only defeat coming at Wolves after Ederson's early red card.
For more than half of the first half, City were able to play the game at a testimonial pace; an embarrassing indictment of both the quality in the United team, and, it has to be said, their apparent growing disconnection to their manager's approach. Previous year here they lost to Paris St-Germain [in the Champions League] and qualified.
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