Henrikh Mkhitaryan has been ruled out for the rest of the season with a knee injury.
The Arsenal midfielder sustained the knock in the win over Bologna on Wednesday and will undergo surgery later this week.
Mkhitaryan, who joined Inter Milan from Manchester United last summer, had made just two Serie A appearances since his move to Italy.
Inter have already signed former Manchester City midfielder Fernandinho as their replacement and are now searching for a new player to fill Mkhitaryan's position in midfield.
The Armenian international was a key part of Arsenal's title-winning side last season and has also played a significant role in Inter's successful start to the season.
He scored three goals and provided four assists in eight league games before sustaining the knee injury against Bologna.
Mkhitaryan's absence could be a blow to Inter's chances of challenging for the Serie A title this season.
But they may be able to turn to other options in midfield, such as the likes of Marcelo Brozovic or Nicolo Zaniolo, if they need cover.
Overall, it is a setback for Mkhitaryan and Inter, but one that may ultimately benefit them in the long run.