Passarella, sensing the fans had had enough of him, declined to run for office again in Sunday's election and victory went to Rodolfo D'Onofrio, the man he pipped to the post four years ago.
More than 17,000 club members turned out to vote at the Monumental stadium where defender Passarella lifted Argentina's first World Cup in 1978, sensing the importance of a change of leadership at River to recover past glories.
D'Onofrio and his board, who take charge on Tuesday, will have to decide on the future of coach Ramon Diaz.
Diaz won a record seven titles in two previous spells but his team performed poorly in the Inicial championship won by San Lorenzo on Sunday.
Among those likely to be involved in the decision on the coach is former Uruguay forward Enzo Francescoli, a River idol since playing a leading role in the capture of several trophies including their second Libertadores Cup triumph in 1996 under Diaz.
"I'm going to meet with (Francescoli) in the coming hours to start drawing up the plan we have," D'Onofrio told the state news agency Telam on Monday.
"He's going to be our first recruit to strengthen the side. If he could play it would be perfect," joked D'Onofrio.
The 52-year-old Francescoli, who was on D'Onofrio's losing election ticket four years ago, could be named sporting director at River who have won an Argentine record 34 league titles and are famous for their attacking style.
The conveyor belt of talent at the club appears to have dried up with Argentina striker Gonzalo Higuain the last world class player to emerge.
He was transferred as a teenager to Real Madrid in December 2006.
Equally galling for River supporters is the fact arch-rivals Boca Juniors took over in terms of producing young talent under the presidency of Mauricio Macri, now mayor of Buenos Aires, in the first decade of this century.