Forward Stephan El Shaarawy will miss AC Milan 's Champions League game against Ajax after getting injured again in training.

El Shaarawy had been included in Milan's squad for the match but shortly after announcing the 20-man list on Monday, the club said the striker has a ''microfracture of the fourth metatarsal in his left foot'' and would not travel to Amsterdam.

The 20-year-old El Shaarawy has been sidelined for nearly a month with a muscle injury and Tuesday's match was set to be his first appearance since Sept. 1.

The Italy international expressed his disappointment on Twitter, saying ''I don't believe it!''

Milan has not announced how long El Shaarawy is expected to be out, but coach Massimiliano Allegri later said he expects the forward to be sidelined for around ''20-30 days.''

Among the games El Shaaraway will miss is Sunday's Serie A clash against two-time defending champion Juventus . He will also miss Italy's World Cup qualifiers against Denmark and Armenia, although the Azzurri are already guaranteed a spot in next year's tournament.