The midfielder was seen limping off at the end of Italy's defeat to Costa Rica on Friday and the chief medic has revealed he is suffering from a calf injury
Daniele de Rossi is "very unlikely" to be fit for Italy's final group game against Uruguay, the team doctor has revealed.
With both the Azzurri and the South Americans losing to Costa Rica and beating England, they head into the final match level on points, yet Italy's better goal difference means a point will secure qualification.
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"It is highly unlikely De Rossi will be able to play against Uruguay," Castellacci said in a press conference.
"There are no lesions to the soleus muscle, but it's an injury that requires a few days to recover from.
"He felt pain during the second half and it intensified towards the end of the game. The tests showed bruising on the calf, that will very likely stop him from playing against Uruguay."
Castellacci gave updates on some of the other players in the Italy squad, revealing that Matti de Sciglio is fit to return to the squad after missing the first two matches, while Claudio Marchisio and Andrea Barzagli are available for Cesare Prandelli.
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“Barzagli is being monitored at the moment. He wasn’t in bad shape today so if his condition stays this way then he can play."
The doctor admitted that players are suffering in the intense heat and humidity in Brazil, but insisted teams stop blaming the conditions for poor performances and defeats.
"According to Fifa's statistics, we played against Costa Rica with a temperature of 28.9 degrees and 65 per cent humidity. In Natal, the climactic conditions should be similar to those in Recife. If it rains, perhaps it would be better for us.
"People must stop emphasising the temperature. It is just one of the variables in a tournament, albeit an important one. It certainly damaged us, as Costa Rica are more accustomed to it, but that is certainly not the reason we lost.
"We will try to improve the situation, but we remain convinced that we did everything we possibly could to contain the climate problem."