Arsenal defender William Saliba broke his fifth metatarsal in Saint Etienne’s 1-0 win over Monaco on Sunday.
The 18 year-old, who joined the Gunners this past summer in a £27m deal, is set for a length spell on sidelines which will now halt his progress.
Saliba was immediately sent back on a season-long loan and has been performing impressively for Etienne this season after missing several opening matches at the start of the campaign through injury.
He has been an ever-present in the team since returning from an abductor muslce injury at the end of September, helping his side keep three clean sheets and move to eighth in Ligue 1.
It’s a big blow for the Frenchman who could now be out for a number of weeks.
Unai Emery will need his current crop of defenders to be at their best when the Gunners travel to Leicester on Saturday for a huge Premier League clash.