كتب : Sherif Tarek
Lukas Podolski broke the deadlock after eight minutes before Miroslav Klose added the second four minutes from the half-hour mark.
Thomas Muller and Cacau completed the rout midway through the second half, scoring on 68 and 70 minutes respectively.
Australia played with a man down for more than half an hour after receiving his marching orders in the 56th minute.
Australia's Good Start
Australia had a good start to the game as they were fiercely looking for an early goal, but their opponents soon controlled the match.
Podolski came unmarked to shoot a Thomas Muller cut-back, to see his effort sting the goalkeeper's palms on its way into the net.
Germany's opener was followed by more opportunities as the Australians struggled amid their opposition's onslaught.
Shortly after Podolski's strike, Richard Garcia tired his luck on 20 minutes with a drive that went wide.
Muller fed Podolski once again with a low cross but the latter missed the target by inches. Klose squandered a similar opportunity seconds later.
But Bayern Munich veteran Klose made amends in the 26th minute when he scored with one of his trademark headers, connecting with a Philipp Lahm diagonal cross.
The thee-time world champions took a stranglehold on the game after seizing a two-goal advantage, while their opponents were unable to get their act together till the break.
Cahill Dismissal
After the restart, Australia redeemed themselves for a while and tried to reduce the arrears before Cahill's dismissal took a toll on the team.
Australia's first clear-cut chance fell to Brett Holman, whose powerful low shot went close past the woodwork.
The Socceroos were reduced to ten men after Cahill received a straight red card for a challenge on Bastian Schweinsteiger.
The TV replay showed that the referee's decision seemed to be particularly harsh.
Germany capitalized on their opposition's numerical disadvantage to regain dominance and carve out a good number of scoring chances.
Muller netted the third after eluding his marker and releasing a low close-range effort that hit the post before settling into the net.
Cacau, who replaced Klose, left Australia with a mountain to climb by adding a fourth goal right after his introduction upon poking home a Mesut Ozil low cross.
The match's goals: