Manchester United have concerns about Casemiro's fitness.
The midfielder has picked up an ankle injury while in action with Brazil in recent days.
Casemiro is a 'doubt' for Brazil's clash with Uruguay in the early hours of Wednesday morning.
The defensive-midfielder requested to be taken off during Thursday's 1-1 draw with Venezuela.
Brazil medical chiefs say Casemiro's injury 'could be worse than first anticipated'. He hasn't trained since the Venezuela draw.