Prior to this setback, Vladan Milojevic men have avoided defeat in their last seven games across all competitions.
The Serbian SuperLiga champions found themselves on the back foot as early as the 11th minute in Italy after Marek Hamsik put the hosts in front.
In the 33rd minute, Dries Mertens doubled the lead with Fabian providing the assist with the Belgian attacker completing his brace in the 52nd minute.
However, the Comoros international scored the consolatory goal five minutes later off Marko Marin’s assist.
Ben Nabouhane will hope to continue the form and add to the 12 goals he has scored in all competitions when his side take on Vozdovac on Sunday.