Five-time champions Australia injected some life into their moribund World Cup campaign with a comprehensive five-wicket victory against Sri Lanka on Monday.

With their backs to the wall after defeats by India and South Africa, Australia showed some urgency with the ball and bundled out Sri Lanka for 209 inside 44 overs with Adam Zampa leading the rout on figures of 4-47.

At 157-1 near the halfway stage, Sri Lanka looked poised to reach the 300-mark before the wheels came off their innings and they had to settle for a below-par total.

After strong winds delayed the start of their chase, Australia made heavy weather of a small target and slumped to 24-2.

Half-centuries by Mitchell Marsh [52] and Josh Inglis [58] put their chase back on track and Glenn Maxwell produced a breezy cameo of 31 not out to see them home with nearly 15 overs to spare.

Australia's first win of the tournament lifted them from the bottom of the 10-team table to eighth place, above 1996 champions Sri Lanka, who remain winless after three matches.

"We didn't say much before the game, but after two losses we wanted to get back to where we know we can be with our high standards," Australia captain Pat Cummins said.

"Their openers started really well and we were staring down the barrel of a big score. But we stuck together, all our bowlers did their job and to finish it off for 209 was a great effort."

Sri Lanka played under a new captain, Kusal Mendis, after Dasun Shanaka's tournament was cut short by a thigh injury.

Mendis elected to bat after winning the toss and a 125-run opening stand between Pathum Nissanka [61] and Kusal Perera [78] appeared to vindicate that decision.

David Warner grabbed two stunning catches to dismiss Nissanka and Mendis while Cummins removed Perera before the bottom half of Sri Lanka's batting order caved in.

"Pathum and KP [Kusal Perera] batted well for the opening partnership but after that the middle order struggled," said Mendis.

"If we could score 290-300, it would have been a good total on this pitch." (Reuters)