Sir Alex Ferguson told leaguemanagers.com: "Obviously we'll point to the Rio Ferdinand suspension, and that will always stick in my throat.
"Simply because we were four points clear. We had the best defensive record in the country. We were playing with great consistency and we usually do well in the second halves of the season, but after Rio's ban, we then hit a spate of injuries.
"Quinton Fortune, first of all, injured himself in training and missed the rest of the season in early Feb, and then Mikael Silvestre got his ankle injury and he was out for three to four weeks. And Gary Neville then got a thigh injury and a suspension, so, when we were playing, our back four was changing every minute.
"There is no question that unless you have a regular back four at that level, going in to that part of the season you are going to struggle, and we did."
"I think that we've got to make sure that we are better. I am not concerning myself with what Arsenal are going to do, I'm only interested in what Manchester United are going to do.
"Our issue is to make sure we're covered better defensively than we were last season, and we'll get that improvement.”
Fergie also spoke of his disappointment over the elimination from the Champions League:
"In the game at Old Trafford, well, I think everybody knows about the refereeing decisions in the game, but, they had only one shot on goal, and then the free kick in the last kick of the game, in the last minute of injury time and everyone was gutted.
"It was so sudden because you couldn't see a goal coming. You could not see them mustering an attack. We handled them really well on the night even though we didn't play particularly well. They didn't give us any problems. Any chances that were made were made by us, so to lose was really disappointing for the players, and hard to take, that."