Wales winger George North faces a race to be fit for the start of the Six Nations after sustaining a knee injury that will require four weeks of rehabilitation.
North made his first appearance since October in Northampton Saints' 50-21 Premiership loss to Harlequins at the weekend after missing Wales' last set of internationals due to an injury to his posterior cruciate ligament, and it is not yet known if the latest knock is a recurrence of the same issue.
The 25-year-old came on as a first-half replacement for Ahsee Tuala before being forced to come off in the 65th minute.
"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," Saints' technical coaching consultant Alan Gaffney said.
"I'm sure George will be diligent in his rehab and we all wish him a swift recovery."
Wales begin their Six Nations campaign with a home fixture against Scotland on February 3.
North is to leave Saints at the end of the season to return to Wales.