City in effect have two days' less rest than Manchester United, who face Newcastle at 4pm on Sunday having had their Champions League group game on Tuesday. Chelsea, the Premier League leaders, kick off at 3pm on Saturday after winning at Nordsjaelland on Tuesday.
Mancini said: "We need to recover very well because we play early on Saturday and I don't understand this. It's incredible that we play Wednesday night and then Saturday at 12.45. We have two days and 12 hours to recover very well.
"We didn't play a good game but we lost a lot of energy in this game and we need to recover. Everywhere else the teams that play in the Champions League play three or four days before the game and have three days minimum afterwards. Here it is strange."
City's stuttering performance against Dortmund ended in Mancini's side grabbing a late point after Mario Balotelli's penalty. This followed indifferent league form that has left them four points behind Chelsea with 16 goals conceded in all competitions.
City, though, are still unbeaten in their championship defence and regarding the club's start Mancini told Sky Sports News: "This year probably we did not play like last year but this is normal because after you win a title the second season is more difficult. It is not a disaster. Every game you have pressure because all people are looking for you to play like how you played the year before but sometimes this is not possible. We have some problems but we are sure we can get better."
City drew 3-3 at home to Sunderland in the corresponding fixture last season, having lost 1-0 at the Stadium of Light .
"It will be very difficult because every time that Sunderland play against us they play a fantastic game," Mancini said. "But there is a connection from Sunderland last year to the Dortmund game. This point in the Champions League will be important and last year the point that we got against Sunderland, when we were 3-1 down with five minutes to go and [Aleksandar] Kolarov equalised, was an important point in the league. We need to remember that game and get three points. It will be a tough game."
Joleon Lescott was again dropped from Mancini's XI against Dortmund after the central defender also missed out at Real Madrid, Liverpool and Fulham. "[This was] for the reason that we play another game in two days and I need four or five fresh players and also because against Fulham the four defenders played well," the manager said. "But Joleon is an important player for us."
Adam Johnson should line up for Sunderland against his former club after he left City in the summer transfer window. "I think that Adam played well here," Mancini said. "The problem was that he didn't always play and for young players like him it's important to play every game. I'm sure he will do well for Sunderland and he's joined another top team. He deserved this because he's a good guy and a good player.
"I hope that he can play a good game on Saturday because I like Adam and he's a really good player. He decided he wanted to go and play every game and he decided to leave."
Martin O'Neill, the Sunderland manager, said: "Has Adam a point to prove? Yes. He will relish going back. He will want to do well and I hope he comes up big in the game. Adam has great talent and terrific ability. He always thought he could hold down a place at City but he did not play often enough. It frustrated him and I hope we can reap the benefit."
Before joining Sunderland Johnson assured O'Neill that his "party lifestyle" had been consigned to history. "I heard a few things about his lifestyle when I was trying to sign Adam," said O'Neill. "I did mention it to him and he assured me that those things were mainly in the past and he has settled down now but the proof will be in the pudding."
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image: © Andrew Brannan