Roberto Mancini said his Manchester City side need "a miracle" after another demoralising defeat in the Champions League on a night when the manager's tactics were questioned by one of his players and he admitted the blame had to be apportioned in his direction.

City's 3-1 defeat against Ajax leaves Mancini's team bottom of Group D, with only one point from their three fixtures and struggling even to qualify for the Europa League. "It's going to be very difficult for us now," Mancini said. "There's one team [Borussia Dortmund] with seven points, one [Real Madrid] with six and one [Ajax] with three. If we win the last three games it will be very close. But it's difficult. It will be a miracle."

Samir Nasri had given City a 22nd-minute lead before Siem de Jong equalised at the end of the first half and Ajax then took control after the break, Niklas Moisander's header putting them ahead before Christian Eriksen's deflected shot completed the scoring in the 68th minute.

"It was probably my fault because I prepared badly for this game," Mancini said. "I didn't prepare the players and I'm at fault. When you prepare for a game sometimes it is a different to what you expect. Sometimes you think the game goes one way and it goes another. We played a bad game. We had a few chances to score but the players didn't really play well."

Mancini started the match with a 4–2–3–1 system, changing it early on to 4–4–2 and then abandoning that for 3–5–2 during the second half. His right-back, Micah Richards, questioned the changes after the match, making it clear there was opposition within the dressing-room to operating with a three-man defence.

"It's not something that we've worked on a lot, we're just used to a back four," Richards said. "But the manager likes it and if we want to do well then we'll have to work harder on it. It's a hard system and I think the players prefer 4-4-2 but he's the manager and we'll do what he says."

Mancini, however, suggested the problem was not solely about the way he set up his team, but also their attitude. "I don't know what he [Richards] said but I don't want to have this. On the pitch we are always 11 players. If you have spirit and quality you can play in the Champions League. If you don't have it, you can't. When you play this game you must have spirit and it is my fault because I should have prepared differently for this game.

"We are a young club when it comes to the Champions League. This is only the second year we have played in this competition. We have three of four important players who are injured who have played in the Champions League every year. But this doesn't change anything. We missed chances. We made mistakes which usually we don't. We didn't have control of the game. Ajax were better on the ball. They moved better than us. Congratulations to them. Usually this is our play and we do this but tonight and against Borussia Dortmund we didn't."

Mancini has used the tactic of publicly blaming himself on at least three previous occasions, the suspicion being that he is trying to create a smokescreen. On this occasion he was even willing to accept responsibility for Joleon Lescott being out-jumped for Moisander's goal, from a routine corner. "It's my fault," he said. "I didn't say to him to jump."