The Red Devils swept to victory, overcoming Scunthorpe United 5-2 in the third round and even though Ferguson was in Spain watching Champions League opponents Valencia in action, Phelan said the cup was of high importance to the club.
"We put a big value on the Carling Cup. We've never set out to demean the Carling Cup. We're holders, we've done that two years in a row and you can see from the players' attitude that we want to keep hold of it," Phelan said.
"He chose to go and watch the Valencia game. We need to go there knowing what we're up against. He's the manager and he had to make a decision."