Favourites Australia and arch-rivals New Zealand were in ruthless form as rugby sevens made its Olympic debut on Saturday, Frenchwoman Camille Grassineau grabbing a piece of history by scoring the first try of the tournament. The Wallabies ran unfancied Colombia ragged in their opening match, Charlotte Caslick scoring a hat-trick in the 53-0 rout. New Zealand look the closest rivals to Australia, with Kayla McAlister -- sister of Toulouse-based former All Black Luke -- and Portia Woodman both outstanding in lop-sided wins over Kenya (52-0) and Spain (31-5).
