The workman fell eight metres as he helped install temporary seating at the ground and was taken to hospital where his condition had been described as serious.
His employers said in a statement yesterday that he was observing all the necessary safety standards at the ground which will host the opening game of the World Cup between hosts Brazil and Croatia on June 12.
In November, two men died when a crane collapsed at the same arena.
A total of seven workers have now been killed during work on Brazil's World Cup venues.
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Yesterday's tragedy came just two days after FIFA secretary general Jerome Valcke had admitted progress on the Sao Paulo stadium remained a concern with the problems compounded by arguments over who foots the bill for temporary facilities.
But Valcke added: "We will have 12 host cities; we will have 12 stadiums....But there is work to do. Time is flying."
"We are helping so that the town hall, the state government and the (private) owners of Corinthians Arena find a solution," Rebelo said.
Earlier this week, Brazil's Development Bank released the first two-thirds of a USD 160 million loan to complete the stadium project.
But confusion remains over who finances some USD 20 million 'overlay' or temporary facilities.
Despite the tight timetable, Valcke said on the basis of talks with constructor Odebrecht he was confident of progress.