George North is a major doubt for Wales' Six Nations opener against Scotland after his club Northampton Saints confirmed that the winger needed up to four weeks of rehabilitation.
North, who has 69 Wales caps to his name, left the field with a knee injury 65 minutes into Saints' heavy 50-21 defeat to Harlequins at Twickenham last weekend.
Wales begin their championship campaign against Scotland at the Principality Stadium on Feb. 3, meaning North faces an uphill task to be fit in time.
Speaking about the wing's injury, Saints' technical coaching consultant Alan Gaffney said: "While it's disappointing that George will be missing ahead of Saturday's game, this injury means an opportunity for another player in the squad to step up to the plate.
"I'm sure George will be diligent in his rehab and we all wish him a swift recovery."
North will leave Northampton to return to Welsh regional rugby at the end of the season on a dual national contract. However, his new region has not yet been confirmed.