Argentina forward signs five-year deal with the Premier League champions but is set to stay in South America until the summer.
Manchester City have completed the £14 million ($18m) signing of River Plate forward Julian Alvarez on a five-and-a-half-year contract.
The Argentina international, who turned 22 on transfer deadline day, will remain on loan at River until July at least.
Alvarez, who scored 20 goals in 35 league appearances for River last season as well as registering nine assists, was a target for a host of European clubs, including Manchester United, Real Madrid and Barcelona.
