Injuries are threatening to rule the Black Stars' defence pair of Isaac Vorsah and John Mensah out of Saturday's crucial Group D encounter against Australia in the ongoing 2010 World Cup in South Africa.Whilst Isaac Vorsah, who has not been training for days is a big doubt, John Mensah who has been suffering from a nagging back ache may have to pass a fitness test.Ghana will play Australia at the Royal Bafokeng Stadium, Rustenburg, at 14:00 GMT.The two players were very instrumental in Ghana’s important win over Serbia in the opening game last Sunday. The development has come as a big blow to soccer fans back home in Ghana having watched their spectacular performance in defence in the last game.Coach Milovan Rajevac has likely replacements in Lee Addy, Rahim Ayew and Jonathan Mensah, and is upbeat about Ghana’s chances against Australia.A win against Australia will hugely boost the Black Stars' chances of making it to the next round of the tournament. Their last game is against Germany who suffered a shocking Serbia by a lone goal early on Friday.Many Black Stars followers are hopeful Ghana can walk over Australia to make Africa proud.Ghana managed to reach the knockout stage in the previous tournament in Germany, their first-ever appearance at the World Cup.Meanwhile Ghana’s Vice-President John Mahama says he is confident that the African teams will do the continent proud despite their poor showing so far at the tournament.The African teams have not done so well so far with Ghana being the only side to record a win. But speaking on South Africa’s Supersport channel, Vice-President Mahama said he still has confidence in the teams.The race in Group D, like other groups, remains widely open.Story by Isaac Essel/Myjoyonline.com/Ghana