Gianluigi Buffon's involvement against England on Saturday night has been thrown into doubt after he limped out of Italy's training session.
The 36-year-old goalkeeper, who has already played at three World Cups, was forced off earlier than planned during training due to an ankle strain.
Cesare Prandelli remains hopeful that he will be fit enough to start their Group D opener, and refused to confirm whether the problem was serious enough to have an impact on his tournament.
"It's a minor strain," Italy's head coach told reporters in his pre-match press conference in Manaus. "He's undergoing therapy."
Salvatore Sirigu would be expected to replace Buffon if he is prevented from starting the match, with Mattia Perin the third goalkeeper included in the squad.