Calum Chambers will miss the rest of the season and faces a fight to be fit in time for next season after rupturing his anterior cruciate ligament.
The defender was taken off after just 23 minutes of the London derby against Chelsea at the Emirates Stadium on Sunday, and, as reported by earlier in the week, Arsenal confirmed that the 24-year-old suffered a ruptured ACL.
The defender has undergone surgery and will now undergo a period of rehabilitation in order to return as soon as possible.
In an injury update on their official website, Arsenal confirmed the news. "Further to the injury sustained during the match against Chelsea on Sunday, we can confirm that Calum ruptured the anterior cruciate ligament of his left knee," it read.
"Calum has had successful surgery in London on Thursday morning. The rehabilitation process is expected to take between six to nine months.
"Everyone at the club will be supporting Calum to ensure he is back on the pitch as soon as possible."
Chambers had been enjoying an extended run in the first team this season, playing 18 times under Unai Emery, Freddie Ljungberg and new head coach Mikel Arteta.
And he has sent a message to the Gunners supporters following the news of his long layoff, saying he is "determined to come back stronger" from the setback.
In a message on his official Twitter account, he said: "Devastated to end 2019 like this!
"If there’s one message I’d like to get across it’s that I’m DETERMINED to come back stronger than I’ve ever been before!
"I would like to say a massive thank you for all the messages and support I’ve been given over the last couple of days!"
