City go into the meeting on Sunday??sitting fourth in the Premier League table after three defeats in their last five league matches, while United will be looking to move further ahead of their rivals in the league with a sixth successive top-flight win.
But Aguero said he is unsure what to expect from Louis van Gaal’s side: “They are a team with a lot of great individual players, who can form an incredible unit when they work well together. But this season that has not always been the case.
???Some matches they don???t seem to play at the maximum, with the attacking qualities that they have in the team. But then in other games, they have really shown that those qualities, so they are a bit unpredictable. We know we will have to be at our very best to beat them ??? there???s no doubt about that.???
Aguero also offered his backing for Radamel Falcao, who has scored just four goals for United since joining on loan from Monaco last summer.
???He isn???t having an easy time this season, but I really admire his commitment and his class and qualities are permanent,” said Aguero. “He is probably one of the most naturally gifted strikers in football at the moment.???
Like Falcao, Aguero has also struggled in front of goal recently and has not found the net for 556 minutes.
However, he has scored six times against United and is aiming to add to that tally at Old Trafford this weekend.
???I always love to score, but of course it is even more special to score in the big games,??? he said.
???If you score against United at Old Trafford it almost give you shivers, because you can feel the tense atmosphere with most of the stadium being really quiet, but the away end going crazy.
???At home at it is different, when the City supporters are really loud in these games, it sometimes gives me goose bumps when they sing my name.???
City go into the derby a point behind third-placed United and nine behind leaders Chelsea, but Aguero still believes they can retain their title.
???Of course we can still win it,??? he said. ???In football, anything can happen ??? as soon as you think something is certain, then everything changes, we have seen it so many times before and we???ll see it again.??
???We only focus on ourselves, try to win every game we play and keep pressure on Chelsea.???