Matthew Rees faces a spell on the sidelines after picking up a groin tear against the Wallabies.
Wales and Scarlets hooker Matthew Rees is likely to require surgery on the groin tear which saw him carried off on a stretcher against Australia at the Millennium Stadium in the final clash of the Invesco Perpetual Series of 2009.
Ospreys wing Shane Williams, who withdrew with a hamstring injury early in the first half, will not require surgery but will be in rehabilitation for a period of four to six weeks.
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."
Nearly 40 players were involved in the first Wales Under 18 training session of the season. WRU National Performance Manager Gethin Watts is excited at the potential shown by the group and expects the Regional Under 18 Championship to hone their skills even further.