Almost 250,000 Confederations Cup tickets bought on the internet by Brazilian fans have not been collected with only two days until the tournament starts, FIFA's general secretary said on Thursday.
Jerome Valcke told a news conference the development raised concerns ahead of next year's World Cup because Brazilian supporters, who have complained about the system, are used to turning up on match day to buy tickets before watching a game.
The problem has been made worse by the reduced number of places to pick up tickets with only one in each Confederations Cup host city except Rio de Janeiro which has three.
Huge queues formed over the last few days in a hotel in Rio and some fans complained of having to wait for over two hours to get the tickets, even with prior appointment.
According to FIFA, world soccer's governing body, 234,000 tickets had not been collected by Wednesday.
"Its good to have the Confederations Cup so the Brazilians can understand that they cant get the tickets on match day, and in the World Cup it will be even more important," Valcke told a news conference on Thursday.
"We need people to get used to buying tickets and to get them in advance," he said.
"Most people in Brazil are used to going to the stadium at the last minute and buying their tickets. That cannot happen in the Confederations Cup and, most importantly, in the World Cup, mainly for security reasons."
A record for the Confederations Cup of more than 800,000 tickets have already been sold out of the 940,000 available.
"We sold three times more tickets in Brazil than in South Africa (in 2009). It's a success," said Valcke.
The tournament starts on Saturday with the opening match between Brazil and Japan in Brasilia. Matches will also be staged in Belo Horizonte, Fortaleza, Recife, Salvador and Rio.