Brazil striker Ronaldo's preparations for the World Cup suffered another blow when he was forced to miss training on Thursday because of illness.
The Real Madrid frontman only returned to training on Wednesday after bad blisters on his feet ensured he could not complete the full 90 minutes of Sunday's friendly victory against New Zealand.
"He woke with a fever and is receiving medication," read a statement on the Brazil Football Federation's website.
Ronaldo had already missed much of the squad's preparations for the tournament as he recovered from the thigh injury that caused him to sit out the final six weeks of the Primera Liga season.
The 29-year-old is expected to feature in a four-man frontline alongside Adriano, Ronaldinho and Kaka for Brazil's Group F matches against Croatia, Australia and Japan.
Should coach Carlos Alberto Parreira decide he is not fit enough to start those games, his place is likely to go to his club team-mate Robinho.