Bhanuka Rajapaksa smashed an unbeaten 33 as Sri Lanka overcame a middle-order stutter to finish on 154 for six against Australia in their Twenty20 World Cup clash on Thursday.

Leg-spinner Adam Zampa returned figures of 2-12 to check Sri Lanka's brisk start after Charith Asalanka and Kusal Perera - both scoring 35 - put on 63 for the second wicket in the Super 12 clash in Dubai.

Pat Cummins struck first with the wicket of Pathum Nissanka in the third over of the innings, but new man Asalanka soon hit bat back with three straight boundaries off the fast bowler.

The left-handed Asalanka kept up the charge and took on Glenn Maxwell's spin as Sri Lanka managed 64 runs off the first six overs of powerplay.

The left-handed pair took on the bowlers before Zampa broke through with his leg spin googly to get Asalanka caught at backward square leg.

Mitchell Starc bowled Perera, a left-handed wicketkeeper-batsman, with a scorching yorker in the next over with Australia making inroads into the opposition middle order.

Zampa took down Avishka Fernando and Starc sent back Wanindu Hasaranga for four as Sri Lanka slipped to 94-5 in the 13th over.

Rajapaksa stood firm to see off Zampa's fourth over before launching an attack as he smashed Marcus Stoinis for two fours and a six in a 17-run over.

The left-handed Rajapaksa and skipper Dasun Shanaka put together 40 runs off 32 balls before the captain walked back for 12 off Cummins.

Rajapaksa hit four fours and one six in his 26-ball knock.

Both the teams are looking for their second successive victory after winning their opening matches in the second stage.