Security concerns are mounting in Rio de Janeiro as the city prepares for the pope's arrival today, after riots last week in some upmarket beachside districts and because Pope Francis has refused to use his armoured popemobile on his week-long visit.
Despite pressure from the Brazilian authorities, the pope will greet crowds at Copacabana beach and Guaratiba, outside Rio, from an open-topped SUV.
Wednesday night's riot began as the latest in a series of demonstrations outside the house of Rio state governor Sergio Cabral. About 2,000 people were involved. Fighting broke out just before midnight and went on for two hours. Bank foyers, newsstands and public telephones were smashed, a shop looted and fires lit on residential streets.
Police used water cannon, tear gas and rubber bullets to disperse protesters. The level of violence in the riot and the fact it took place in such renowned tourist areas shocked the city.
At least six protests are planned during the papal visit - including one today, when Pope Francis is due to meet President Dilma Rousseff, Governor Cabral and Rio Mayor Eduardo Paes at the state government seat, the Guanabara Palace.
General Jose Abreu, who is in charge of 14,300 army, air force and navy personnel drafted in to boost security, said demonstrators wearing masks would not be allowed into open-air events such as the Field of Faith - a two-day outdoor vigil and mass at Guaratiba - and may be expelled if they produce placards.
Students are even planning to camp out by the military base at the Ilha de Governador where Pope Francis's plane is due to land today. A mass gay kiss is also planned.
The Guanabara Palace has already seen confrontations between police and protesters, who have increasingly focused their anger on Cabral.
Protesters want him impeached because of what they say are his links to big business and the heavy-handed police tactics used at previous protests.