Milan did not say for how long Bennacer will be out of action but confirmed to AFP that he will not play again this season as he has to have an operation on cartilage in his right knee.

Bennacer, 25, was substituted in the 17th minute of Milan's 2-0 defeat to their local rivals.

Milan have a huge task to overturn the two-goal deficit in Tuesday's second leg and were lucky not to lose by more as Hakan Calhanoglu hit the post and Inter created a host of opportunities to extend their lead.

Milan are also fifth in Serie A and in a battle to qualify for next season's edition of Europe's top club competition.

(For more sports news and updates, follow Ahram Online Sports on Twitter at @AO_Sports and on Facebook at AhramOnlineSports.)