Juventus sweating on Vidal availability
The Chile international scored from the penalty spot to settle last week's quarter-final first leg tie 1-0 in Turin.
However, the midfielder did not train with the rest of the group on Monday as they prepare for Wednesday's second leg.
A statement on Juve's official website read: "All present [at training] except Arturo Vidal, who did not attend the session as he is suffering from acute tonsillitis.
"His availability for [Tuesday's] training will be evaluated in the morning."