Felipe Massa checked back into hospital on Monday after returning to his native Brazil.
The Ferrari driver spent the previous nine nights in Budapest's AEK hospital, after undergoing surgery for serious head injuries sustained in a Hungarian GP qualifying crash.
Massa, 28, returned to Sao Paulo by private plane on Monday, but according to the Associated Press was later admitted to the Albert Einstein Hospital, where he is expected to remain for two days for tests.
The AFP news agency said the Brazilian was transferred directly to the hospital by helicopter from Sao Paulo airport. Further reports said Massa walked into the hospital on foot.
His father Luiz Antonio Massa said the hospital stay would not be lengthy and involved only check-ups.
