Arsenalhave confirmed that Mikel Merinohas suffered a foot injury and will have 'surgery in the coming days'.
Merino, 29, missed Saturday's trip to Leeds United and Wednesday's Champions League home tie against Kairat Almaty after picking up the issue in last Sunday's 3-2 defeat by Manchester United.
Mikel Arteta said post-Leeds that Merino would see a specialist to determine a full prognosis.
Now, it has been revealed that Merino is set to miss an 'extended period' due to 'bone injury in his right foot'.
A statement from Arsenal read: "Further to sustaining a foot injury towards the end of our game against Manchester United on January 25, subsequent assessments and specialist reviews have confirmed Mikel Merino has a bone injury in his right foot.
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"Mikel will have surgery in the coming days and will then begin his recovery and rehabilitation programme. Mikel is expected to be out of action for an extended period, with the aim of returning to full training before the end of the season.
"Everyone is fully focused on supporting Mikel to ensure he is back to full fitness as soon as possible."
Shortly after Arsenal released that statement, Merino shared a heartfelt message on Instagram and vowed to come back stronger and fitter than ever.
"Time to stop now with a foot injury," Merino said. "Sometimes life throws this kind of challenges when is less convenient. Just another opportunity to be strong, resilient and overcome it. We have the best medical team and together we will come back stronger.
"Thank you all, your support means everything to me and I can’t wait to be back on the pitch soon, helping my team and doing what I love [red love heart emoji] @arsenal @sefutbol."
Merino's injury setback has put Arsenal in a difficult position with 24 hours remaining of the transfer window. Indeed, the Gunners are said to be scouring the market about making a potential loan move for a new midfielder before Monday's 7pm deadline.
The Spaniard has provided six goals and three assists in 33 appearances this season, and has been used as both a central midfielder and a centre forward by Arteta.
Back in December, Arsenal head coach Arteta hinted the Gunners must be prepared to move in the January transfer window to accommodate unexpected blows or opportunities.
"The window is there and I mean we are Arsenal and we have to be looking at it, 'Okay, what do we need?'" Arteta said. "And we have to be actively looking and then, whether we can do it or not, that's a different story. But our job is to always be very prepared because something can happen, so hopefully it'll be very positive.
"When you look across the other clubs, they have 24 or 25 squad players. Although we have had more injuries than expected, some of them not avoidable, we want to be better and we know how important the part of having the right availability with players is going to be this season."
