FIFA secretary general Jerome Valcke on Thursday said work on the Sao Paulo stadium which will host the opening match of the World Cup remains a concern.
A fatal accident at the stadium in November and worries over who foots the bill for temporary facilities has held up progress at the arena where Brazil take on Croatia on June 12 in the World Cup opener.
"We don't yet have a solution," Valcke said following a local organizing committee board meeting in Rio, though he added he was "quite confident" one would emerge by Friday.
"We will have 12 host cities; we will have 12 stadiums," he stressed. "But there is work to do. Time is flying."
Brazilian Sports Minister Aldo Rebelo insisted the authorities were lending their full support.
"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 $160 million loan to complete the stadium project.
But confusion remains over who finances some $20 million 'overlay' or temporary facilities.
Sao Paulo was one of six venues to miss an initial FIFA deadline of December 31 and the stadium is only set to be handed over to organizers in mid-May.
Despite the tight timetable, Valcke said on the basis of talks with constructor Odebrecht he was confident.
"I have full trust in Odebrecht to deliver on time for the opening game," Valcke told reporters at the Maracana Stadium, which will host the July 13 final.
However, initial agreements for the host cities do not make Odebrecht responsible for the cost of the work but rather the owner, Corinthians club.
Valcke said come what may, with 77 days to go until the first match Sao Paulo would definitely stage the curtain-raiser.
"It will happen in Sao Paulo. There is no other choice. It was a decision we made with the LOC and government to keep these 12 cities whatever will be the challenges.
"It will happen in Sao Paulo -- there is no other choice" even if "we will maybe be a bit borderline."
- 'Porto Alegre work to be delivered' -
On Porto Alegre, amid reports local media authorities were prepared to sue FIFA if the organization did not help with temporary facility costs, Valcke said the coming weeks were crucial.
Tuesday, the state legislature in Porto Alegre passed a motion whereby firms contributing to a bill of some $11 million will receive tax breaks.
"In Porto Alegre a solution was found. Now work has to be delivered," said Valcke.
But he added at least part of 140,000m2 of pavement needed to be laid for items such as TV compounds, optic fiber and cabling.
"These are for us the priorities for the next three weeks. There is a lot of work in Porto Alegre - more than in Sao Paulo," where there is a single contractor, said Valcke.
Curitiba and Cuiaba stadiums also remain incomplete, though Valcke said he stood by last month's decision to retain Curitiba after an initial threat to axe it over lagging preparations.
"It was the right decision -- Curitiba will be ready," he insisted.
Brazil may be the most successful nation in the tournament's history, but the giant nation's first World Cup in 64 years has turned into a hot potato for organizers and the government.
Protest groups aghast at the spiraling cost beyond $11 billion -- and with the 2016 Rio Olympics to come -- have promised to disrupt the tournament.
Sao Paulo was due to be the scene of yet another anti-Cup protest march later Thursday.
Opinion polls show support sagging for the event as well as the government -- albeit also sliding for the protests.
A Confederation of Industry poll showed support for the government of President Dilma Rousseff had slumped seven points to 36 percent as she battles against possible negative World Cup fallout in election year.
She still remains favorite to win.
FIFA marketing director Thierry Weil meanwhile issued a warning to would-be World Cup ticket scalpers, telling them they know who has bought each ticket.
"We will take action against those people. We can track every ticket down to the person who has actually bought them."