EXCLUSIVE: *NO DAILYMAIL ONLINE* Serena and Venus Williams heading to training in Adelaide this afternoon, in preparation for the Australia Open Tennis Grand Slam. The Williams sisters were spotted arriving via minivan to the tennis training centre, the area was signposted as a ??sRED ZONE??? and guarded by Police and Health officials Pictured: Serena Williams,Venus Williams World Rights, No Argentina Rights, No Australia Rights, No Bolivia Rights, No Brazil Rights, No Chile Rights, No Colombia Rights, No Costa Rica Rights, No Cuba Rights, No Dominican Republic Rights, No Ecuador Rights, No El Salvador Rights, No Guadeloupe Rights, No Guatemala Rights, No Mexico Rights, No Nicaragua Rights, No New Zealand Rights, No Paraguay Rights, No Peru Rights, No Panama Rights, No Puerto Rico Rights, No Spain Rights, No Uruguay Rights, No Venezuela Rights