A late cameo by Charith Asalanka helped Sri Lanka to 157-6 after Australia's bowlers struck with regular wickets in a key Super 12 match at the Twenty20 World Cup on Tuesday.

Defending champions Australia elected to bowl first in Perth and replaced Covid-hit Adam Zampa with Ashton Agar in the team, which lost their opener to New Zealand last week.

Asian champions Sri Lanka looked in trouble at 120-6 in the 18th over but the left-handed Asalanka smashed an unbeaten 38 off 25 balls to put up a fighting total.

Pathum Nissanka (40) and Dhananjaya de Silva, who made 26, put on 69 runs to lay the foundations for the total but Sri Lanka slipped midway by losing wickets.

The quicks bowled a tight line to start with and Pat Cummins struck in the second over of the match to send Kusal Mendis trudging back to the pavilion for five.

Nissanka, who returned to the team after recovering from a groin strain, and De Silva kept the score ticking and with occasional boundaries to steer the team to 63-1 in 10 overs.

Agar broke the stand after getting De Silva out with David Warner taking a good running catch at long-off.

Asalanka came out and attacked Mitchell Marsh's bowling to hit a six and four after Cummins dropped Nissanka at deep mid-wicket.

But Nissanka soon fell run out after a mix-up with Asalanka.

Big-hitter Bhanuka Rajapaksa smashed a boundary off Mitchell Starc but got out next ball and Sri Lanka soon lost half their side when Glenn Maxwell sent back skipper Dasun Shanaka, for three.

Sri Lanka lost their sixth in Wanindu Hasaranga, but Asalanka stood firm and put on an unbeaten stand of 37 with Chamika Karunaratne, who made 14.

The pair smashed Cummins for two fours and a six in a 20-run final over to finish with a flourish.