Arsenal have been dealt a huge blow after Mikel Arteta confirmed that Martin Odegaard faces an extended spell on the sidelines.

Gunners captain Odegaard injured his ankle playing for Norway earlier this month and was absent for last weekend’s north London derby win over Tottenham.

The midfielder is now set to miss Arsenal’s Champions League opener at Atalanta on Thursday and their massive showdown with Premier League title rivals Manchester City at the Etihad Stadium on Sunday.

Arteta confirmed Odegaard would be out for a lengthy period in what is a major setback for Arsenal.

“The scans showed that he’s got some damage especially on one of the ligaments in the ankle. It’s something quite significant so we’re going to lose him for a while,” the Arsenal boss said at his pre-Atalanta press conference in Bergamo on Wednesday night.

“He’s our captain. He’s been one of the biggest and best players in our team. Our identity is very linked to how he plays and behaves. It’s a big test for the team to see how able we are to show a different face.”

Odegaard injured his ankle playing for Norway against Austria in the Nations League earlier this month, limping off in the second half of the match in Oslo. The midfielder then flew back to London and was photographed getting onto a plane with the aid of crutches.

Norway doctor Ola Sand came out later that week and said that Odegaard was likely to be out for at least two to three weeks.

“Such ankle injuries often take at least three weeks. Anything other than that is just a bonus, and then it can take longer,” Sand told Norwegian newspaper VG.

“What we have so far obtained from the MRI examination in London is that there is probably no fracture in the ankle.

“It is always a bit difficult to interpret an MRI scan when you have had an old injury, but Arsenal are almost certain there is no breach - but this may still take some time.

“In the event of a fracture, we are talking about being out of action for six weeks plus.”

There was better news from Arteta on Bukayo Saka and Riccardo Calafiori, both of whom are available to face Europa League holders Atalanta on Thursday.

“Riccardo was able to train today and he will be in the squad,” Arteta said. “Saka was able to train today and completed most of the session so he's available.”

Oleksandr Zinchenko, Mikel Merino, Takehiro Tomiyasu and Kieran Tierney are among Arsenal’s other current injury absentees, though Declan Rice is now available again after missing the north London derby through suspension.