Daniele De Rossi is almost certain to miss Italy's crucial final Group D game against Uruguay on Tuesday with a leg injury, the team's doctor has said.
"He has a muscle problem in his leg and it is highly unlikely that he will be able to play," Enrico Castellacci told a news conference on Saturday.
"If I was being positive, I would say it is possible that the injury to the muscle would improve -- but it is highly improbable he will play."
De Rossi's likely absence means Thiago Motta is poised to come in alongside Andrea Pirlo for a game in which Italy need a point to go through with Costa Rica at Uruguay's expense.
If the Italians do progress, Roma player De Rossi may not be fit for their round of 16 game, with doctors suggesting he could need a week or more to make a full recovery.
But coach Cesare Prandelli has been given better news about defender Andrea Barzagli, whose tendinitis problem should not prevent him from playing his third game of the tournament.
His fellow defender Mattia De Sciglio, who did not play in either of the opening two matches because of a calf strain, is back in training and available for selection.
Castellacci said there were no further fitness concerns -- but stressed that Italy's players needed to be wary of the heat of Natal in their early kick-off.
"The players felt it [the heat against Costa Rica]," he said. "Against Uruguay, it will impact both sides in the same way."