The World Cup kicks off in Brazil today after years of construction delays and budget overruns.
Protests and labour strikes are planned in the 12 host cities, including a 24-hour slowdown by some airport workers in Rio de Janeiro.
However, the threat of a long subway strike in Sao Paulo has eased.
Some businesses in Rio, the venue for seven games including the final, had boarded up windows and doors yesterday in case protests erupted.
Brazil's national team hosts Croatia in the opening match at a newly-built stadium in Sao Paulo, the cost and late delivery of which came to embody the troubled World Cup preparations.
Hundreds of thousands of soccer fans will descend on the country for the month-long tournament.
However, many Brazilians are angry over the €8.3bn spent on hosting the World Cup when basic social services are poorly financed.
Massive street demonstrations hit the country last year.
Although they have faded in numbers recently, officials expect a hard core of a few hundred people to try to block traffic to the stadium today.
That could cause violent clashes with police.
Brazilians say the country will rally as soon as the action starts, especially if their team justifies its billing as favourite to win the tournament for a record sixth time.
President Dilma Rousseff dismissed complaints about the heavy spending and delays in preparing stadiums and airports, and said Brazil will put on a show on and off the field.
"What I'm seeing more and more is the welcome given to the teams and the happiness of the Brazilian people with our team," she said in a speech yesterday.
The list of possible problems is long with the main risk, for both fans and the government, appearing to be violent street demonstrations.
Officials privately expressed fears that protests and traffic problems could mean some fans might still be stuck outside the Arena Corinthians in Sao Paulo when the opening match starts.
The government has decreed a partial holiday for today to help ease congestion.