"Ronaldo had a little strain on the inside of his thigh and Nemanja [Vidic] missed Serbia's game on Wednesday while on international duty," Ferguson told MUTV. "We'll see what they are like for Tuesday but they were not fit for Saturday."
"I think we had enough players to win that game, there's no question about that," he said. "But Bolton did make a lot of chances and they worked really hard for their victory. You cannot deny them that.
"We didn't make enough chances to say we deserved to win the game. If we had scored we would probably have won it but we needed to score."
While obviously disappointed with the result, Ferguson urged his players to bounce back immediately.
"We have to react to losing the game. It's in the history and nature of our club and we have the right set of players to do that."