Both team started with equal ball possession and scoring opportunities but Jacob Whettin broke the defence barrier to give the Australians 1-0 lead in the ninth minute of the match.
Pakistan equalised in the 13th minute with a goal from Muhammad Irfan on a penalty corner.
After two-quarters and the half-time mark the score was 1-1 but Daniel Beale gave the Australians much deserved lead on a penalty corner in the 32nd minute.
Read: Pakistan down Poland 2-1 in opener
Mattew Swann and Jamie Dwayer then made sure to apply pressure on Pakistan with two goals in the span of seven minutes. Both field goals were scored in the 42nd and 49th minute of the match.
Pakistan goalkeeper Imran Butt was impressive throughout the match with his quick reflexes to deny the world number one team on a number of occasions but Blake Govers found an opportunity and scored in the 54th minute of make it 5-1 for the Kookaburras.
Govers ended the match with another goal in the 58th minute as Australia bagged three important points in Pool A to go on top. They beat France 10-0 in their first match.
Read: And so begins the road to Rio
Pakistan, meanwhile, are third in the Pool with three points from the 2-1 win against Poland.
Pakistan will now face the subcontinent arc-rivals India on June 26. They have to win the next two matches in order to move into the quarterfinals.
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