The forward fractured a vertebra in Brazil's 2-1 quarter-final win over Colombia on Friday when Juan Zuniga kneed him in the back in the second half.
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But CBF head doctor Jose Luiz Runco strenuously denied Neymar could be fit for the final, while the Brazilian governing body declared that it would report any doctors who had recommended pain-killing injections for breaching medical ethics.
Reports in the Brazilian media suggested that the doctors at Santos - Neymar's former club - had told both the player and his family that he could recover quickly enough to play in the final at the Maracana.
"There is absolutely no chance that Neymar will play," Runco told ESPN, however.
"Right now, Neymar has a stable injury to his spinal column, which needs bone healing.
"If the injury received any further impact it could become unstable, which would cause problems both to Neymar the player and the human being."