Roberto Mancini believes Manchester City's Premier League title defence threatens to be undermined by outside forces.

The Italian was at his cryptic best following a battling 4-3 Carrow Road win for his side which was marred by Samir Nasri's first-half dismissal following an aggressive altercation with Sebastien Bassong.

Mancini conducted a series of post-match interviews which ranged from claiming the Blues would appeal Nasri's red card to insisting the precocious Frenchman would be fined and dealt with internally.

Mancini also claimed Bassong should have been sent off, alongside Nasri, and hinted at different treatment from the officials towards his club compared with their rivals.

Mancini stopped short of directly criticising the men on duty at Carrow Road, with the Italian already facing an FA probe into post-match comments made towards referee Kevin Friend following their Boxing Day defeat at Sunderland.

'There are two rules for different teams, and I hate this in football and cannot accept this,' he said. 'In life, there is only one rule for everyone. This season, I have seen things which are not good. For the referees, this is the most easiest thing to do, but I do not want to talk about the referees too much, because I said last time that they had a big lunch for Christmas, and I don't know what (will happen).

'After the sending off for Samir, with 10 men it was difficult, we continued to play but I don't know what he got the red card for – I don't know what the linesman saw. The linesman was very close but I don't know, we saw the video – both players touch each other's heads, it was nothing.

'I think the linesman should pay attention. I don't know if they've changed the rules in the last three or four months, I don't understand what I just saw here. I don't know either why it's possible for a goalkeeper to touch the ball with his hand when it came off his own defender – I've seen some incredible things in the last four or five games.'

Mancini refused to absolve Nasri, who was dismissed for an attempted head butt, but the Manchester City boss was adamant Bassong should also have walked for a strong sliding challenge which sparked the fracas.

'Both players came forward with their heads, so if you are going to send off one, then you have to send off both, not only Samir,' he said. 'Samir said he touched his head, okay, but the other player has done the same. The linesman has a big responsibility also, because it was not a good decision, it is incredible.

'You want to send off both players? Then, okay, the referee was there, he saw everything. The linesman was behind (the players), he could not see. We will appeal, sure. I am disappointed with Samir, and he will pay his fine, but the decision was not correct. Samir did a mistake, okay, but after why when the other player did the same thing, does he send off only one?'

Mancini was convinced Nasri's dismissal a couple of minutes before half-time decisively altered the flow of an inevitable win for the champions after Edin Dzeko's early brace had put the visitors in total command prior to Anthony Pilkington's deflected free-kick.

'It changed the game. If not we would have won this game with no problem,' he said. 'With 10 players it is difficult. Norwich is a good team. 10 versus 11 players is not easy, but today we showed that we are there for the title because we don't leave this easy.

'We will fight every game and also with 10 players the guys were fantastic. I am delighted with the result and the performance.

'In the first few minutes, we played some fantastic football and scored two goals – we deserved to score three or four goals, but after the sending off it was difficult, however, we fought well. For us now it's not important to look at the table because it's not final. We need only to work, to win many games in a row and then maybe we'll look again at the table in February.'

Mancini's faith in restoring Dzeko to his starting line-up was rewarded after Carlos Tevez had mis-fired on Wearside earlier in the week. Tevez had to settle for place on the bench on his first Norfolk return since firing a hat-trick in April.

'Edin did very well today, he scored two or three goals. Clearly if the strikers score, it's easy,' said Mancini. 'We decided to play Edin in the last three days, because now we play three or four games in 10 days, we need all of our players to be fresh. He scored two important goals. I am happy but I was also happy with Carlos and Sergio (Aguero) at Sunderland. We deserved to win. We played well. We were missing only a goal but every year it is like this. We have 23 or 24 chances to score there and we end up losing. That is in the past but we have now won this important game.

'We need players fresh and I hope Dzeko can play well. He got his chance here and he scored goals.'