Natal is the latest FIFA World Cup venue to draw concern from football's governing body FIFA after it was revealed thousands of seats at Dunas Arena are yet to be installed.
FIFA secretary general Jerome Valcke posted images on Twitter on Wednesday showing vacant swaths of stands where seats are supposed to be, reports Xinhua.
"Race against the clock. Still lots to be done for World Cup fans and media," Valcke said on the social media network after visiting the stadium.
"We need full commitment from all parties in Natal to ensure all will be in place & tested prior to #MEXCMR on 13/06," he added, referring to the Group A clash between Mexico and Cameroon on June 13.
Dunas Arena is one of four World Cup stadiums yet to be ready, despite guarantees from local authorities that all 12 venues would be complete by last December.
The 42,000-seat stadium will host four World Cup matches.