A fan of River Plate throws a stick onto the field after their Argentina's first division second leg playoff soccer match against Belgrano in Buenos Aires June 26, 2011. [Photo/Agencies]

BUENOS AIRES - The mayhem that swept River Plate's Monumental stadium following the famed team's relegation to Argentina's second division also threatens the future of club president Daniel Passarella and the upcoming Copa America.

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Police officials on Monday said 89 people were injured and 55 detained in riots sparked by rampaging fans, humiliated by the club's demotion despite a history that includes 33 league title - more than any other Argentine club.

The fallout from the loss has already cost jobs. Coach Juan Jose Lopez quit on Monday, the club said on its Website, and was replaced by former club midfielder Matias Almeyda. Passarella's position as president is also under threat, but the 1978 World Cup winner says he won't be quitting.

A prosecutor has ordered the stadium to be closed until the turnstiles can be inspected. He has suggested the legal capacity of 40,000 was exceeded by 12,000. The stadium, which also serves as Argentina's national stadium, is set to hold the final match of the Copa America on July 24.

Argentina is the host nation for the Copa America _ the South American national team championship _ with play starting Friday in La Plata, 60 kilometers (35 miles) southeast of Buenos Aires. Argentina and Brazil are the favorites to meet in the final, which could again test security at the aging stadium.

Prosecutor Gustavo Galante said the closure could last for a month, but also hinted it might take only a week to gather evidence.

"We are going to look for evidence of what happened," Galante told The Associated Press. "The stadium will remain closed until this is completed and all the evidence is in hand."

CONMEBOL, the governing body of South American football, insisted the match will go on.

"Fans can rest easily," spokesman Nestor Benitez told The AP. "The Copa America final will be played at River Plate's stadium."

Ernesto Cherquis Bialo, a spokesman for the Copa America and the Argentine Football Association, said it was too early to know if the final would be moved. He also said AFA's executive committee would meet Thursday and decide on sanctions against River Plate.

Sunday's rioting was set off after River Plate drew 1-1 with Belgrano in the second leg of a relegation playoff, which followed a 2-0 loss four days earlier. That match was suspended for 20 minutes when River Plate fans ripped through a fence and raced across the field to taunt their own players.

The chaotic scenes Sunday pitted River Plate hooligans known as "Los Borrachos del Tablon" - the Drunks in the Stands - against a force of 2,200 police, the largest to ever patrol an Argentine football match.

Enraged fans were sprayed with high-power water hoses - inside and outside the stadium - with police using teargas, rubber bullets and hand-to-hand combat in a futile attempt to control the rioting.

Inside the stadium, fans ransacked concession stands, ripped the slats from seats and swung them at police.

As fans scattered outside, they set fire to vehicles and rubbish bins around the stadium in the leafy suburb of Nunez, with many smashing windows and breaking into shops in upscale shopping areas.