Astrada takes charge of River again
Astrada, who was in Argentina's 1998 World Cup squad and ended his first spell as River's coach four years ago, confirmed he had accepted the job on TyC Sports cable TV.
"We've just agreed my appointment (with the club board) and from tomorrow I'll start working with the team," said Astrada, who takes over from Nestor Gorosito after he quit on Sunday.
River, who threw away a 1-0 lead in the last seven minutes to lose 2-1 at San Lorenzo on Sunday, are 16th in the Apertura championship with five points and one win in seven matches.
Astrada, 39, steered River to the Clausura championship in 2004 and the Libertadores Cup semi-finals in 2004 and 2005, having won the South American trophy playing for them in 1996.
He has since coached at Rosario Central, Colon de Santa Fe and Estudiantes.
Astrada's first match in charge will be on Monday against another of the country's biggest clubs, Independiente, coached by former River Plate and Argentina midfielder Americo Gallego.