On a dramatic day in Group D that also saw Tunisia beat world champions France, Leckie’s moment of magic proved the difference.
After a turgid first-half in which Denmark could not apply the finishing touch to a number of slick moves, the Melbourne City winger punished such profligacy with a moment of magic.
With the Socceroos entrenched in their own half, Leckie launched into a searing counter attack just before the hour mark, twisting and turning the Danish defence before steering the ball past Kasper Schmeichel.
While tipped as dark horses in some circles before the tournament, Denmark were defeated in rather meek fashion. Rarely did they truly threaten Mat Ryan and never looked convinced they would add to the one goal they had scored in Qatar heading into kick-off at the Al Janoub Stadium.