Brazil striker Fred could be sidelined for the next three months with a thigh injury.
Scans Monday revealed that damage to Fred's right quadriceps muscle was worse than first thought, local newspaper Estado de S.Paulo reported.
The Fluminense star suffered the injury during his team's 0-2 loss to Santos in the Campeonato Brasileiro last Saturday.
The 29-year-old has been replaced in Brazil squad for Saturday's international friendly against Australia by Corinthians forward Alexandre Pato.
Australia were also dealt a blow when former Everton midfielder Tim Cahill withdrew from the match in Brasilia with an ankle injury.
The New York Red Bulls veteran was forced off the field early in the second half during his team's 2-1 victory over DC United in the MLS.