Alex McLeish's side have been given a week off to recharge their batteries ahead of Saturday's home clash with Bolton.
Blues won the Carling Cup and also reached the last eight of the FA Cup, but a demanding programme, combined with a growing injury list, has taken its toll.
But Ferguson said: "It has been a tough schedule but I am not going to use that as an excuse. I honestly don't believe that tiredness comes into it. This is what you do as a football player.
"You want to play in these sort of games and you realise that if you go on a cup run you are going to play extra games.
"It's what we are mentally and physically prepared for."
Source: PA
Source: PA