Socceroos goalkeeper Mark Schwarzer believes Australia's makeshift defence is ready to rise to the occasion in their World Cup qualifier against Iraq in Qatar.Coach Holger Osieck has been forced to change the left side of Australia's starting backline, with Matt McKay and Matthew Spiranovic replacing the club-less David Carney and injured Sasa Ognenovski respectively.The national team's defence has come in for criticism since the start of the final round of World Cup qualifying in June.With Australia sitting on two points after three matches, the Socceroos need their defenders to hold firm against world No.80 Iraq in Doha on Tuesday night (Wednesday morning AEDT).Schwarzer said McKay and Spiranovic were up to the task."They've played there before, they're all very experienced boys," he said."We've had the time now, nearly a week under our belts to work on the training field."It's been very positive."Osieck said playing midfielder McKay at left back was a temporary move."It's just an emergency solution," he said."Right now due to the fact there are no alternatives."Whoever would have come into consideration is not available."There are maybe three others for that position, (Michael) Zullo, (Jason) Davidson and (David) Carney, but for different reasons they are not here."So the only option I see is Matty because he is very versatile, he's a very intelligent player and he can adapt to different positions."