AC Milan have revealed Alexandre Pato has suffered a tear to his thigh.

For the draw with Napoli, Pato lasted only 10 minutes before pulling up and calling for a substitution.

"AC Milan announce that Pato underwent medical tests to discover a first degree tear in the right femoral bicep, at the junction with the tendon," read the statement.

"In the next few days Pato will undergo further tests."

It is not clear how long he will be out for this time, but reports suggest anything up to three weeks.