Media claim Chile and Cagliari forward Mauricio Pinilla was punched in the face by a member of the Brazil staff.
The incident is said to have happened during the half-time break of Saturday’s 1-1 draw, which the Seleçao eventually won on penalties.
Brazilian paper Globoesporte insists the director of communications of the Brazilian Federation Rodrigo Paiva punched Pinilla.
Chile director Maria Jose claims it was caught on camera by FIFA crews and demanded an investigation.
Globoesporte also questioned Paiva, who said he was really trying to reach Chile assistant manager Sebastian Beccacece and the punch on Pinilla was an accident.
Tickets for the Champions League final between Juventus and Real Madrid are still on sale with reseller Viagogo - Click to find out more