Arsenal have announced that defender Hector Bellerin has ruptured the anterior cruciate ligament of his left knee.
The defender is expected to be out for between six and nine months, the club confirmed on Tuesday morning.
He suffered the injury during Arsenal’s derby win against Chelsea at the weekend.
The Spaniard will now be sidelined for the rest of the campaign and possibly also the start of next season.
Bellerin went down unchallenged during the second half of Arsenal’s 2-0 victory and was carried off on a stretcher.
The 23-year-old was making his first start since mid-December having overcome a calf problem.
Arsenal revealed the severity of Bellerin’s injury with a statement on their website.
“Further to the injury sustained during our match against Chelsea on Saturday, we can confirm that Hector has ruptured the anterior cruciate ligament of his left knee,” it read.
“Hector will undergo surgery to repair this in the coming days. The rehabilitation process is expected to take between six to nine months and therefore rules Hector out of action for the remainder of this season.
“Everyone at the club will now be working as hard as we can to ensure Hector is back on the pitch as soon as possible next season.”