City's Sergio Aguero vows to gun-down United at Old Trafford in Sunday's Manchester derby

Sergio Aguero has vowed to end the worst scoring drought of his Manchester City career at Old Trafford on Sunday.

Aguero has gone six matches without finding the net as City's alarming tailspin since the New Year has accelerated.

The Argentina striker netted 19 in just 21 appearances before suffering a medial knee injury in early December.

But since returning after a month out, he's managed only four from 14, two of them penalties.

With Edin Dzeko and new boy Wilfried Bony also struggling for goals, City have scored 21 less than at the same 31-game stage last season as their hopes of retaining their title have effectively ended.

But Aguero is encouraged by his scoring record in Manchester derbies - six in seven games - and hopes to extend the sequence against a United side that he describes as "unpredictable".

"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 gives 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."

Aguero admits City, who have slipped from joint first on New Year's Day to fourth after taking only 15 points from a possible 33, will have to rediscover their best form to beat a United team who have moved above them for the first time since Sir Alex Ferguson retired on the back of five successive League wins.

And he is not sure 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," he said.

"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."

City go into the derby a point behind third-placed United and nine behind leaders Chelsea, who have a game in hand, but Aguero still believes they can retain their title after coming from behind to win pip United to the championship in 2012 and Liverpool last season.