Marcus Stoinis smacked a muscled fifty that guided Australia to earn a net run rate-lifting win over Sri Lanka as they thrashed them by seven wickets in the Super 12 of the ICC T20 World Cup in Perth on Tuesday.

Stoinis smashed an unbeaten 18-ball 59, his fastest fifty in the T20Is, to take the hosts to 158-3, chasing down a moderate 158-6 with 21 balls to spare.

Skipper Aron Finch stood on 31 off 42 balls.

Dhnanjaya de Silva, Chamika Karunaratne, and Maheesh Theekshana took one wicket each.

Pursuing a modest 158, defending champion Australia made a cautious start as they catapulted to 24 after 4 overs before they lost their opener, David Warner, in the very first delivery of the next over for 11 off 9 balls.

Mitchell Marsh followed in the footsteps of his colleague after three overs, scoring a slow 17-ball 18 to apply pressure to the side.

However, in the third wicket stand, Glen Maxwell and Aron Finch formed a 29-partnership to exceed hundred for the side before the former was removed for a flurry of 23 off 12.

That was the end of the worry for the side, as in the next stand, a whirlwind 69 off 25 from Finch and Marcus Stoinis pulled the Aussies to the harbor of victory.

For Sri Lanka, Pathum Nissanka made a highest 40 off 45 balls and Charith Asalanka stood on a gusty 25-ball 38.

Josh Hazelwood, Pat Cummins, Mitchell Starc, Aston Agar and Glenn Maxwell scalped one wicket each.

Sent to bat, Sri Lanka made a wobbling start as they lost their opener Kusal Mendis for 5 prior to the final delivery of the second over that shortened them to 6-1.

In the next stand, Dhananjaya de Silva and Pathum Nissanka added 69 off 58 balls to stitch the innings before the former was dismissed on 26 off 23 balls followed by the removal of his fellow partner for a sluggish 45-ball 40 leaving the side on 97-3.

However, the island encountered a debacle in the penultimate overs, losing Bhanuka Rajapaksa, Sasun Shanaka, and Wanindu Hasaranga inside 23 runs, which reduced them to 120-6.

In the middle, Charith Asalanka hit an unbeaten 25-ball 38 while an undefeated flurry of 14 off 7 balls came from the tail-ender Chamika Karunaratne to power Sri Lanka to 157-6.