The powerful forward scored the opener in Internazionale`s win over Reggina, but limped out of the game on 29 minutes.
Early indications from the Inter camp are that the injury is not too serious, but the decision has been taken to withdraw Vieri as a precaution.
Azzurri coach Giovanni Trapattoni has drafted in Lazio striker Bernardo Corradi as Vieri`s replacement.
Italy are already without star duo Francesco Totti and Alessandro Del Piero, meaning Trapattoni may have to go with an inexperienced forward line against Portugal.
Inter are also sweating over the fitness of Turkish midfielder Emre after he picked an ankle injury in the clash with Reggina.
Emre was forced to leave the Giuseppe Meazza on crutches, but Inter coach Hector Cuper is hopeful that the duo are not too badly injured."Let's hope they could recover for next engagment," said Cuper.
