Brazilian authorities blocked suspected members of Argentina's violent hooligan gangs from entering the country and closely watched thousands of Argentine fans who filled the streets of Porto Alegre ahead of their team's Wednesday match with Nigeria.
Authorities in this southern city 700 kilometers (430 miles) from the Argentine border expected 80,000 Argentines to arrive for the World Cup match — only a quarter of them holding tickets for the game.
Around 30,000 fans had arrived by Tuesday afternoon, said Antonio Candido, spokesman for the city's public security department. Many were sleeping in the vans or cars they drove in.
Boisterous fans filled bars and streets close to Beira-Rio Stadium, but so far there had been no violence.
"We think they're coming to have fun," Candido said.
Brazil's federal government said that since the World Cup began June 12, it had blocked 32 people suspected of being part of Argentina's hooligan gangs from entering the country — 18 by air and 14 by land. It said they were identified using a list of 2,000 names provided by Argentina.
The visitors in Porto Alegre were being allowed to camp in downtown parks, Candido said. Some 20,000 people would be able to watch the match at a "Fan Fest" public viewing area set up by international soccer's governing body, FIFA. A second video wall was being set up in the city to accommodate an additional 30,000 people.
While the fans had been good-natured so far, the city of about 1.4 million people was taking precautions.
"We know we could have problems, so we are ready for everything," Candido said.
The World Cup so far has been largely peaceful, although drunken Argentine and Brazilian fans clashed briefly on a street in Belo Horizonte on Saturday and there were two incidents of ticketless fans attempting to break into stadiums.
On Tuesday, hundreds of Argentine fans gathered close to the Porto Alegre stadium, drinking alcohol and singing.
Police in riot gear and on horseback closed off a section of the street and then lined up in front of them, but there was no menace in the air.
One supporter, Jose-Maria Forcado, said he was trying to buy a ticket for the match, which he said were being offered for around $1,000.
"We will drink and party all day, but there will be no fighting," he said.