Squad captain Ryan Jones should be back in training this week after a back injury forced him to watch from the sidelines at the weekend and Leigh Halfpenny has joined the Baa-Baas squad still undergoing treatment for a dead leg.
"It is unclear at the moment as to the extent of Matthew's problem and we are currently in consultation with specialists but it is fair to say there is a strong likelihood that he will be requiring surgery and we will know more once that surgery has been undertaken," said Wales team physio Mark Davies.
"With Shane things are a little clearer, he has a grade two tear to his hamstring and will be out of action for four to six weeks undergoing treatment and rehab.
"Ryan will link back up with the Ospreys this week and should be taking some part in training and conditioning but will obviously be managed by his region. Leigh has reported for Baa-Baas duty and will receive treatment during the course of the week which should improve his situation."