Julian Alvarez, an Argentine attacker, has joined Manchester City for 17 million euros (£14.1 million).
The 22-year-old has signed a five-and-a-half-year contract with City and will stay with the Argentinian champions until July.
The Premier League winners came upon a condition in Alvarez’s contract that required him to be released during the signing process.
Julian Alvarez has scored 36 goals in 96 games for River.
His skill distinguishes him as one of South America’s most promising young players.
Julian Alvarez made his Argentina debut last summer and was a member of the team that won the Copa America this year.
“I truly believe we can offer him with the ideal circumstances to fulfil his potential and become a great player,” City director of football Txiki Begiristain stated.
Brito claimed Julian Alvarez had to leave River in an interview with CBS News on Sunday.
“With all Julian has done, it was always inevitable that his release clause would be reached,” Brito told Fox Sports Premium in Argentina.
“The most difficult part was agreeing on a loan because Julian is nearly unreplaceable in the team.”
“It’s a nice agreement since he gets to stay with us for a little longer and joins a major club, one of the best sides in the world with tremendous economic power,” River coach Marcelo Gallardo said.
“City don’t need him right now, and we don’t have to go out and get a player of his calibre, which would be impossible.”