The 29-year-old winger underwent tests on his injury to assess the problem, according to a statement on the Italian Football Federation's official website, and his progress will be monitored by medical staff.
Captain Gianluigi Buffon initially took to the training field at the team's base in Montpellier, but returned to the gym soon after the session began after feeling unwell, according to Sport Mediaset.
Italy secured first place in group E on Saturday when Belgium beat Ireland 3-0, meaning that Antonio Conte's side cannot be caught in top spot and will face group D's runner up in Paris on June 27 in the last 16.
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(Reporting by Ed Dove; Editing by Ian Chadband)
