"I can tell you that we are far, far advanced [in Russia]. Even, I would say, we have more problems actually in Brazil than... here," Blatter told a news conference.
Blatter said last month that the South American country still had problems with airports, roads and public transport.
Later on Friday, Blatter backtracked, saying he had received an encouraging report from FIFA General Secretary Jerome Valcke about progress in Brazil's preparations for the 2014 finals.
"I received a very encouraging report from FIFA General Secretary Jerome Valcke after his visit to Brazil this week. In this context, I would like to reiterate we are convinced Brazil will organise a fantastic FIFA World Cup 2014 on schedule," a FIFA statement in Portuguese quoted Blatter as saying.
"In my comment earlier in Russia - which led to some misunderstandings - I was referring to the excellent preparations in Russia up to the moment, since they are ahead of schedule for the FIFA World Cup 2018," he said.
"Regarding Brazil, I am very satisfied with the strong commitment in the last few days by the Brazilian government under the leadership of Sports Minister Aldo Rebelo and I am anxious for us to continue on our walk together towards 2014."
Russia won the right to stage the sports' biggest event for the first time when it beat England and joint bids from Spain/Portugal and Belgium/Netherlands in December 2010.
Blatter and UEFA chief Michel Platini were visiting St Petersburg to celebrate the centenary of the Russian Football Union.
