AC Milan star Mario Balotelli could be set to miss his side's Champions League clash against Spanish giants Barcelona on Tuesday, according to Goal.com.
The Italy star, who scored for his country in midweek, returned to the San Siro injured following the international break.
The 23-year-old has become a vital player for Milan since his move from Premier League side Manchester City in January 2013.
But the forward may now be sidelined.
A statement released on Milan's official website read,
"AC Milan announces that Mario Balotelli is suffering from a vastus intermedius muscle injury to the right thigh.
"The player will be monitored in the coming days in order to better define the extent of the problem and determine the prognosis."
Balotelli has 15 goals in just 17 league games since leaving the Etihad, and would be seen as Milan's main threat on the Barcelona goal.
His side host Udinese at the weekend, and will want to get back to winning ways after losing their last Serie A game against title rivals Juventus.