Mikel Arteta has confirmed that centre-back Gabriel is injured and will be out for "weeks" ahead of the north London derby against Tottenham Hotspur on Sunday.
The Brazilian was forced off in his country's match against Senegal last Saturday just after the hour mark, where he was pictured holding his thigh.
Watch: Arteta's update on Gabriel's injury
What did Arteta say?
"Gabi is unfortunately picked up an injury with the national team. He will be out for weeks," Arteta said in his pre-match press conference.
"We need to have another scan next Wednesday. We will have the timeline much more clearly than we have at the moment.
"It's clearly a blow. It's our leader in our backline. To miss him is never a positive thing. The good thing is we have some very good options. They need to stand up now."
How many matches could Gabriel miss?
The Brazilian may be absent for as many as 11 matches until the end of December.
This includes a hectic week where Arsenal play Spurs, followed by Bayern Munich in the UEFA Champions League, before a trip to Stamford Bridge to face Chelsea.
Gabriel could also miss huge tricky away matches at Aston Villa (6 December) and Everton (20 December).
The matches Gabriel could miss
| Date | Opponent | Competition |
|---|---|---|
| 23 Nov | Spurs (H) | Premier League |
| 26 Nov | Bayern Munich (H) | Champions League |
| 30 Nov | Chelsea (A) | Premier League |
| 3 Dec | Brentford (H) | Premier League |
| 6 Dec | Aston Villa (A) | Premier League |
| 10 Dec | Club Brugge (A) | Champions League |
| 13 Dec | Wolves (H) | Premier League |
| 20 Dec | Everton (A) | Premier League |
| 23 Dec | Crystal Palace (H) | EFL Cup |
| 27 Dec | Brighton (H) | Premier League |
| 30 Dec | Aston Villa (H) | Premier League |
Who else is injured for Arsenal?
The Gunners are dealing with a number of absences at the moment, with as many as eight players sidelined with various injuries.
This includes captain Martin Odegaard, forwards Viktor Gyokeres, Kai Havertz and Gabriel Jesus, along with wingers Noni Madueke and Gabriel Martinelli.
See: Latest Premier League injuries
Who could replace Gabriel?
Summer signings Cristhian Mosquera and Piero Hincapie are two who could fill the void in central defence.
Mosquera has settled in well since joining from LaLiga side Valencia in the summer, making 12 appearances in all competitions and helping the Gunners keep eight clean sheets in those matches.
Hincapie, who joined from Bayer Leverkusen on deadline day this summer, has made five appearances in various competitions after recovering from a groin injury.