"We dominated the game for 90 minutes, had so many chances, could've killed it off three or four times, but we relaxed and were punished".
Despite the gap in the table, both sides go into the game in good form and on the back of strong Champions League performances - United won 2-1 away at Juventus while City thrashed Shakhtar Donetsk 6-0.
"But what is behind I can not say but in this moment I have only to think about football, and to think about football is to think about Manchester City as a football team there".
Manchester United have been given a scare leading into Sunday's Manchester derby with club-record signing Paul Pogba missing training on Friday.
Paulo Dybala has revealed what he said to Jose Mourinho after confronting the Manchester United boss as he taunted the Juventus fans on Wednesday night.
"So, I just want to play the match as an isolated event: hard match against a very hard team. We will make a final decision after the weekend", Martinez said.
If City win they will be 12 points ahead of United, but Guardiola, who will be without Kevin De Bruyne, added: "Win or lose they are not out of it". "I don't think that's the way to look at the match".
"They are a very good side, they play good football, they score a lot of goals in every game, but we also have our qualities which we have to use. A difficult match against a difficult team but they think it is a difficult match for them".
"If the answer is positive, he's ready but in this moment I can only say he trains with the team, I don't know his answer".