Fourth seed Venus Williams [ Images ] retired from her Australian Open [ Images ] third round match against Germany's [ Images ] Andrea Petkovic with injury on Friday after lasting just seven points.

The seven-times Grand Slam champion pulled up with what appeared to be a groin strain after lunging for a return with the German leading by a game and 30-0 in Melbourne [ Images ].

- Images from the Australian Open

Petkovic moves on to face former champion Maria Sharapova [ Images ] in the fourth round.

Williams strained a muscle in the same area during her second round victory over Czech Sandra Zahlavova on Wednesday.