Arsenal have confirmed that Henrikh Mkhitaryan has a metatarsal fracture and is expected to return to training in six weeks.
The Armenia international has featured sporadically for Unai Emery's side thus far this season, making 14 Premier League appearances but completing 90 minutes just six times.
He has scored four goals and provided one assist domestically, however.
Mkhitaryan played the first half of the Gunners' 2-0 defeat to Tottenham in the League Cup, but was substituted at half-time and was subsequently missing from the Premier League clash with Burnley.
The 29-year-old received treatment following a tackle from Lucas Moura in the 30th minute but saw out the rest of the half.
However, Mkhitaryan sat out the Gunners' 3-1 victory over Burnley on Saturday and is not anticipated to return until February.
The midfielder will miss clashes with Premier League leaders Liverpool and Chelsea, while Arsenal's meeting with Manchester City on February 3 is likely to come too soon.
Unai Emery's defensive troubles continue with Nacho Monreal a doubt to face Brighton and Hove Albion on Boxing Day due to a right hamstring issue that forced him off in the first half against Burnley.
However, Shkodran Mustafi is expected to return to full training this week, having missed Arsenal's last four outings due to a hamstring injury.
The Gunners are currently fifth in the Premier League, though they sit level on points with fourth-placed Chelsea, with only goal difference separating the two teams.
They are, however, 11 points behind league leaders Liverpool.