Italy centre-back Giorgio Chiellini's continued participation in the European Championships is at risk due to a hamstring injury.
The 27-year-old limped out of Italy's 2-0 win over Ireland on Monday night and team doctor Enrico Castellacci said afterwards the signs weren't good.
"These injuries never have immediate recovery periods but we'll have to wait for the tests we'll conduct in a couple of days," he said.
Coach Cesare Prandelli was more positive, expressing his belief that Chiellini - as veteran of Euro 2008 and the disastrous 2010 World Cup finals campaign - would make Sunday's quarter-final in Kiev.
"I have faith in our great physios and medical staff to get him ready," he added.