Fresh from winning gold at the Beijing Olympics, the Argentina defender joined on an five-year contract from Spanish club Espanyol.

City did not disclose details of the deal.

'He's young and a winner, with an Olympic gold medal to prove that, but more so he will provide us with great balance in the side,' City manager Mark Hughes said Sunday.

'I'm very happy to bring him here and hopefully we can get a good result at Sunderland to round off what has been a very satisfactory week indeed for us.'

City also signed Israel defender Tal Ben Haim from Chelsea and Vincent Kompany from Hamburger SV this offseason, along with Brazil striker Jo and England winger Shaun Wright-Phillips. -- AP