Wales winger George North is a doubt for the side's opening Six Nations fixture against Scotland after sustaining a knee injury while playing for his English club Northampton Saints.
George North of Wales shows sign of pain after a hamstring injury
North returned from a lengthy lay-off due to a knee ligament injury, which ruled him out of Wales' November internationals, including the defeat to Australia in Cardiff, as a substitute in Saturday's 50-21 defeat by Harlequins and picked up another knock to the same area.
Saints said that the 25-year-old British & Irish Lion star will require up to four weeks of rehabilitation.
"I'm sure George will be diligent in his rehab and we all wish him a swift recovery," Northampton Technical Coaching Consultant Alan Gaffney said on the club's website.
North, who has 69 caps for Wales, is the latest to join a lengthy injury list for Warren Gatland's side, with the likes of Taulupe Faletau, Sam Warburton, Jonathan Davies and Dan Lydiate also sidelined.
Wales kick off their Six Nations campaign against Scotland on February 3.