The two countries meet at Itaipava Arena Fonte Nova in Bahia on Friday (Saturday morning AEST) in what is the final friendly for both sides before the tournament begins in Brazil.
Kovac's men defeated Mali 2-1 before leaving for South America and he feels the encounter with Ange Postecoglou's players will prove a more valuable run-out.
"Against Australia we will get the answer to one or two more questions," he said.
"There is always the chance of injury, but there is that chance in training too.
"We wanted the match primarily to adjust to the climate as it's one thing to train in Austria and play in Osijek as opposed to playing serious opponents in Brazil."
While the Socceroos' hopes of getting positive results against Chile, the Netherlands and Spain have largely been written off, Kovac - who must lead his team against hosts and favourites Brazil in the tournament opener - believes Australia are capable of defying the odds.
"Australia play nice, vertical and aggressive and can surprise at the World Cup. We're striving for a positive result."
The Socceroos play Croatia in a friendly on Friday night (kick off 9am AEST time Saturday morning live on Fox Sports) ahead of their tournament opener against Chile on June 13.
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