Struggling AC Milan have been dealt a blow after Lucas Biglia's knee injury worsened to a point that means he faces an unspecified period out of action.

Biglia has played in 10 out of Milan's 11 Serie A matches this season, with Vincenzo Montella's men eighth in the table after winning only one of their last six league games.

The Argentina international has been suffering from the problem for some time, confirmed club doctor Gianluca Melegati, with no timescale set for his return.

Biglia is not expected to be available for Milan's away Europa League game against AEK Athens on Thursday, nor their Serie A match at Sassuolo on Sunday and has been forced out of the Argentina squad.

"Biglia has an inflammation of the left tendon: a discomfort that he senses for a while, but as a great professional he has always given his availability," Dr Melegati told Milan TV.

"But now the pain in the area of inflammation has increased, so we decided to stop and take some time to recover."

Biglia had been named in Jorge Sampaoli's Argentina group for a pair of November friendlies against Russia and Nigeria, but has now been replaced by Stuttgart's Emiliano Insua.