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Manchester City have formally announced the signing of Sergio Aguero from Atletico Madrid on a five-year contract for a reported £40m.

The 23-year-old has been the most sought-after striker in world football since he said he wanted to leave Atletico in May and his decision to sign a five-year deal with City will raise already sky-high expectations that they can challenge Manchester United for the Premier League title.

Aguero, seen as the natural replacement for fellow Argentine Carlos Tevez who wants to leave the club, said he was ready to fight to help City achieve their ambitions.

"My style has always been to fight to the death for every ball, and give 100 percent every game," Aguero, who scored three goals in four games in Argentina's disappointing Copa America campaign, said in an interview on Manchester City's website.

"I'll be concentrated to the maximum in everything I do, movement, running off the ball, winning the ball back and scoring goals..."

"To be honest, I don't think I'll have too many problems settling in to the team," added Aguero, whose transfer fee was reported to be around 45 million euros (£40 million) which would eclipse the sum they paid for previous record-signing Robinho.

"I'll do my best to do what the manager asks and try to work the way he wants me to. Of course he will know how he wants to use me."

Aguero said he had signed for Champions League debutants City to challenge for major trophies, having watched on television as the club won its first silverware for more than 40 years by beating Stoke City in the FA Cup final.

"I saw the FA Cup victory last season," Aguero said. "I think we are a team that in the future will be fighting every year to win major trophies and let's hope its quite a few major trophies."

Aguero, who married one of Argentine great Diego Maradona's daughters, will wear the No.16 shirt at City and could get his first taste of action in this weekend's pre-season Dublin Super Cup tournament, the club said on its website.

"I've only heard good things about the squad and can't wait to get to know them," said Aguero, scorer of 74 goals in 175 appearances for Atletico during his five-year stay in the Spanish capital.

City, who are bank-rolled by Abu Dhabi billionaire Sheikh Mansour bin Zayed Al Nahyan, have already been spending heavily in the summer transfer window which closes at the end of August.

French left back Gael Clichy was signed from Arsenal while Mancini also pounced for highly-rated Serbian defender Stefan Savic from Partizan Belgrade.