The 31-year-old Springbok was dropped awkwardly by team-mates on his head and shoulder while attempting to field a restart on the opening weekend of the southern hemisphere's premier club competition.
Matfield has already been ruled out of this week's clash with the Auckland Blues but the overall damage could yet be worse for the 6ft 7in lock.
The initial prognosis of the injury suggests that Matfield will be out of action for two-three weeks but he faces an anxious wait for the result of x-rays to determine if the injury is any more serious than at first thought.
Matfield has a tear in his AC joint and is now hoping that the shoulder joint itself has not been damaged further.
Having been voted man-of-the-match in the 2007 World Cup Final win over England, Matfield moved to France to play his rugby for big-spending Toulon last season.
With the Lions tour on the horizon, Matfield decided to return home during the summer and is likely to be one of the cornerstones of the Springbok pack for the three-Test series against Ian McGeechan's men in June and July of this year.