Paul Pogba has been advised to have an operation to address his ankle injury, according to Manchester United manager Ole Gunnar Solskjaer.
Solskjaer had expected Pogba to be fit to join the United squad against Arsenal but revealed that the midfielder's ankle problem could leave him sidelined for longer than anticipated.
Pogba played in United's 2-0 defeat at Watford on December 22, making a rare appearance in a three-month spell of injury problems, and featured again when United beat Newcastle United 4-1 on Boxing Day.
After watching his side lose 2-0 to Arsenal at Emirates Stadium, Solskjaer was asked how long he expects Pogba to remain on the sidelines, and he told BT Sport: "I don't know, three or four weeks maybe.
"He's been advised to have an operation by his people and he'll probably do that."
Solskjaer went on to clarify the club's involvement in Pogba's treatment, telling reporters: "He's had scans, it's nothing major, it's something that has to be sorted within a timeframe.
"He's been advised to do it soon as, and he'll probably do it soon as. We have had consultants looking at him. The scans have been done by us."
United went behind to a Nicolas Pepe strike after eight minutes in North London, and Arsenal doubled their lead through Sokratis Papastathopoulos just before half-time.
Solskjaer suggested his players may have been affected by fatigue after playing five games in 13 days prior to the trip to Arsenal.
"We started off decent but didn't capitalise on the two or three counter-attacks we had," said Solskjaer.
"We were too slow to things and too slow on the ball. That's credit to them because I thought Arsenal played really well. On and off the ball I thought they were excellent. We had some tired heads, maybe.
"We kept going, we pushed them back, created half-decent chances but the quality in our finishing wasn't good enough."