Alex Zanardi is back in intensive care.
After a full month in a hospital in Siena, Italy, following a horror hand-cycling crash, the Italian was moved to a rehabilitation centre last week.
His son Niccolo said there had been "encouraging signs" since Zanardi's sedation was stopped, and hoped the 53-year-old would soon be able to communicate with his family.
However, La Gazzetta dello Sport now reports that Zanardi is back in an intensive care unit - this time the San Raffaele hospital in Milan.
La Repubblica said the decision to transfer the former driver was because of his "unstable condition".
"His clinical conditions became unstable and it was necessary to transfer him from Villa Beretta to an intensive care unit," the newspaper reported.
Claudio Zanon, director of the rehabilitation clinic, said: "It was decided that from now on no more information about the case will be published."
La Gazzetta dello Sport believes Zanardi, who according to the rehabilitation clinic's priest was in and out of consciousness, has a high fever due to a bacterial infection.