Four of the 12 venues are still not ready and at least two will not be completed until at least April, two months before Brazil meet Croatia in the opening match on June 12.
Authorities are also racing against the clock to finish airport terminals and transport systems and to clean up areas around the grounds.
Officials at soccer's ruling body FIFA have expressed concern but can do little more than cross their fingers and hope everything is alright on the night.
"I am not a World Cup specialist but I will say this has not been easy for sure," FIFA secretary general Jerome Valcke told reporters in Zurich at the weekend.
"I think things will work well but it is also true that whenever you receive something late it becomes a challenge to make it ready in time."
Valcke, the man charged with organising the tournament, prompted a diplomatic uproar in 2012 when he said Brazil needed "a kick up the backside".
President Dilma Rousseff replied by vowing this would be "the World Cup to end all World Cups", a slogan repeated by FIFA boss Sepp Blatter, but others say there are reasons for scepticism.
Two of the completed arenas have already shown signs of wear and tear, with part of the roof at the Mineirao stadium in Belo Horizonte falling off at the weekend. No one was hurt in the incident.
"Only when stadiums are completely ready can you train people to work inside them," said Jose Roberto Bernasconi, president of the National Association of Architectural and Consulting Engineering Companies.
"There are stewards, security, plumbers, fire safety officers. When you have 65,000 people inside the ground including kings, presidents, prime ministers, everything has to work.
"Remember when Heathrow opened Terminal Five a while back?", asked Bernasconi of the London airport. "They lost hundreds of bags.


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