Striking subway workers called a demonstration in Sao Paulo on Monday, pressing on with a walkout threatening to cause transport chaos at the World Cup opener in three days.
The five-day-old strike has already caused massive traffic jams in Brazil's largest city as its new stadium prepares to welcome more than 60,000 fans for Thursday's Brazil-Croatia game.
The 9,000-member union plans to protest Monday morning at a central metro station where police used tear gas and truncheons to disperse strikers last Thursday.
The Homeless Workers' Movement (MTST), a mainstay of the anti-World Cup protests that have shaken Brazil over the past year, and other activist groups also plan to take part.
The protest comes as World Cup teams continue arriving in Brazil, with reigning champions Spain touching down Sunday night.
The US, France, Argentina, Uruguay, Ecuador, Costa Rica, Honduras and Cameroon are all expected Monday.
After that all but five of the tournament's 32 teams will be on the ground.
But the chaos gripping Sao Paulo — the latest in a wave of strikes and protests around the tournament — has distracted the usually passionate footballing nation from the World Cup buildup.
Union president Altino Melo dos Prazeres told subway workers Sunday they should seize on the tournament and elections later this year to pressure the authorities.
The five-line subway system has been partially operating, but trains were not arriving at Corinthians Arena, which will host the opening game.
Monday's protest promises to add to commuters' headaches in the sprawling city of 20 million people, known for its terrible traffic even when public transport is running normally.
The workers have reduced an initial demand for a 16.5-percent wage hike to 12.2 percent, but employers are offering only 8.7 percent.
Brazil's World Cup tarnished by economic woes
Rising inflation and a sluggish economy have tarnished the World Cup glow in Brazil, fueling the anger of strikers and protesters who say the $11-billion budget would have been better spent on education, health and transport.
Authorities are keen to resolve the latest labor dispute and avoid further embarrassment in a World Cup hit by delays and cost overruns even before it has started.
Corinthians Arena has become a symbol of the problems besetting the tournament.
At the weekend workers were racing to finish the 61,600-capacity stadium, which has been chronically behind schedule and over-budget.
Work on the 12 host stadiums has also been overshadowed by accidents that have killed eight workers. Three of the deaths were at Corinthians.
President Dilma Rousseff, who is seeking reelection in October, insists the money spent on the tournament will leave a legacy of modernized airports and transport infrastructure that will benefit Brazil for years.
But many of the promised projects have been shelved.
A year ago during the Confederations Cup, a World Cup dress rehearsal, more than a million people flooded the streets, some trashing property and clashing with police.
While recent protests have been smaller, organizers will be nervously watching Monday's demonstration for signs that last year's "Tropical Spring" could reemerge.