AC Milan will be without Ignazio Abate for at least two weeks after the defender was diagnosed with a right thigh muscle injury, the Serie A side said on Thursday.
Abate lined up for Milan's Champions League match at home to Malaga on Tuesday but was replaced after six minutes.
Milan went on to draw the match 1-1, a result which sent Malaga through to the last 16 knockout phase and left the hosts second in Group C, a point above Anderlecht with Zenit St Petersburg two points further adrift.
Milan said Abate would be sidelined "for at least 15 days" after which time the club would "undergo further checks".
It means he is likely ruled out for the trip to Anderlecht on November 21, and possibly the final group game at home to Zenith.
After their worst start to the league season Milan, champions in 2011 and runners-up last year, sit 10th after 11 games on just 14 points -- half that of champions and leaders Juventus.