River Plate is facing demotion to the second division for the first time, and Argentine security officials are bracing for possible violence with more than 2,000 police assigned to the match at River's 50,000-seat stadium.

The Buenos Aires club must win Sunday's game against second-division Belgrano by two goals, or it will be relegated for the first time in its 110-year history.

Belgrano won 2-0 at home on Wednesday in the first leg, which was stopped in the 52nd minute when dozens of River Plate hooligans - at least one wearing a mask - ran onto the field and pushed and taunted River players.

Any outcome is potentially volatile in a country where football-related violence in and out of stadiums has been blamed for 14 deaths in the last 16 months.

''It would be a very tough blow for Argentine football if River goes down,'' said Juan Roman Riquelme, midfielder for River's archrival Boca Juniors.

The object of fan anger has been club president Daniel Passarella, the captain of Argentina's 1978 World Cup-winning team and a star defender at River Plate.

The club is training in isolation on the outskirts of Buenos Aires, but TV images have shown Passarella running practice in place of coach Juan Jose Lopez.

Police with shields and batons marched behind a water cannon on Thursday, scattering several hundred demonstrators who tried to confront Passarella at his office in River Plate's Monumental Stadium.

The decision by Interior Ministry officials - after talks with the Argentine Football Association - to hold the match in a full stadium was announced on Thursday with many saying it should be played without fans. The deployment of more than 2,000 police is believed to be a record for a football match.

The nonprofit group, Let's Save Football, says 257 people overall have died in football-related violence in the country. It has blamed the AFA for much of the recurring violence, saying President Julio Grondona has ignored hooligan groups who often stir up trouble.

The AFA says the violence is a social and police issue, not a football one.

''The lack of control is enormous,'' said Monica Nizzardo, president of Let's Save Football, in an email to The Associated Press. ''This match (Wednesday) crossed the line and put fans' lives, and players' live, at risk. We are in a country where even a 90-minute sports event isn't safe.''

River will be without three key players suspended for the game: Captain and midfielder Matias Almeyda, and defenders Paulo Ferrari and Adalberto Roman.

River Plate has won 33 league titles - 10 more than any other club - but its performance has been in free fall recently. The club - known by the nickname ''The Millionaires'' - has debts reported at $19 million and has sold off many of its top players to European clubs, hoping to save itself.