World Cup organizers have fretted for a year over the possibility that a resurgence of mass anti-government protests could mar soccer's premiere event.
Yet in recent weeks Brazil's public sector has become the main worry. A series of strikes by public transport workers, police, teachers and others across the country is proving more disruptive than protests, and some fear they could cause chaos during the tournament that begins in a week.
On Thursday, subway and commuter train operators went on strike in Sao Paulo, just one week before Brazil's biggest city hosts the World Cup's opening match. Authorities are counting on the subway to be main way that soccer fans get to Itaquerao stadium for the game.
Striking teachers in Rio de Janeiro blocked main roads during the evening rush hour, snarling traffic in that city.
If such strikes continue, "there will be chaos during the World Cup," said Carla Dieguez, a sociologist at Sao Paulo University's School of Sociology and Politics.
"What we don't know is how long the strike will last and if workers in others cities where games will be held will also go on strike," she said about the subway and train strike.
A two-day walkout in April by state police officers in the northeastern World Cup host city of Salvador led to a spike in homicides and robberies. One week earlier a police strike in the city of Fortaleza, also a World Cup host, brought widespread looting during two days.
Last month, a 48-hour strike by Sao Paulo and Rio de Janeiro bus drivers left hundreds of thousands of people unable to get to and from work, while civil police in 14 states went on a 24-hour work stoppage demanding higher wages. The police strike affected at least six cities that will host World Cup games: Rio de Janeiro, Sao Paulo, Salvador, Manaus, Recife and Belo Horizonte.
Federal police agents, who oversee immigration at international airports, and state police officers responsible for keeping order on the streets have said they may strike during the World Cup despite an injunction from the Supreme Court ordering them not to halt work during the tournament.
The authorities and courts haven't shown any ability to force public workers in services essential to the World Cup to show up for their jobs.
Late Wednesday a judge had ordered Sao Paulo's train operators to work at full capacity during rush hours and at 70 percent capacity in off hours. Union members voted to go ahead with the strike anyway, disdaining the judge's order that the union be fined $44,000 each day it ignores the ruling.
The union said on its website the strike would continue until officials met its demand for a pay hike of at least 10 percent. The Sao Paulo state government company that runs the subway system has offered an 8.7 percent increase.
The potential trouble from striking public workers has overshadowed earlier worries about disruptions from protests fed by simmering anger over the billions spent by governments to host the World Cup while Brazil's schools, health system and public transit have widespread problems.
Last year, huge protests took over streets in dozens of cities during the Confederations Cup, which is international soccer's warm-up tournament for the World Cup. On just one night, a million people were out in the streets across Brazil to join in demonstrations.
Violent clashes between young protesters and police erupted at many of last year's protests, and threats by some groups to organize demonstrations during the World Cup raised concerns about security during the tournament.
But while there have been almost daily protests in the weeks before the tournament, the marches have been far smaller than a year ago.
The subway strike in Sao Paulo illustrated the potential for disruptions during the World Cup. The more than 3.5 million people who use the city's public transit systems on weekdays faced chaos as only three of the five subway lines operated, and with limited service.
Enraged commuters smashed in doors at some stations when they arrived to find them closed. The station nearest Itaquerao stadium was damaged by irate travelers who kicked down metal barriers at two entryways and some jumped onto the tracks to protest.
Meanwhile, people lined up for long waits at bus stops before squeezing into packed buses for long rides on Sao Paulo's notoriously congested streets.
"It is opportunism. They want a pay raise and are using the World Cup as a tool," said Pedro Araujo, an annoyed truck driver. "Yes, we want to fight for our rights and for what is fair, but not like this, affecting everyone."
Associated Press writers Bradley Brooks in Rio de Janeiro and Adriana Gomez Licon in Sao Paulo contributed to this report.