Since the start of the 2022 World Cup Lionel Messi has scored 12 goals across his past 10 games for Argentina
Captain Messi, 35, opened the scoring after one minute and 19 seconds, curling a finish into the top left corner from the edge of the box.
Substitute German Pezzella doubled the world champions' lead with a header in the 68th minute.
Australia's Mitch Duke had a first-half effort pushed onto the post by Aston Villa goalkeeper Emiliano Martinez.
But Argentina always looked comfortable in Messi's first match since agreeing to join American side Inter Miami.
Lionel Scaloni's side were playing their third fixture since lifting the World Cup in December, and their first outside of Argentina.
-- Courtesy of BBC Sport