After his side won the toss on Wednesday (AEST), Adam Zampa (4-12) was again the star attraction as Australia skittled Namibia for only 72 runs - the lowest total any side has ever posted in a T20I against Australia.
From there, Travis Head (34no) top-scored with the bat as Australia (1-74) posted its fastest-ever successful run chase in a T20I.
Skipper Mitch Marsh (18no) hit the winning runs for four past deep extra cover after only 34 deliveries.
Adam Zampa was the star performer in a strong bowling effort. (AP PHOTO)
"I thought it was a great performance from our bowling team, we want to try and take early wickets," Marsh said.
"There was a bit of swing out there, it's a beautiful wicket. All round, a professional performance."
Australia will now finish in the top two of Group B, meaning they will play in the tournament's Super 8 stage regardless of the result of Sunday's final group-stage match against Scotland.
Finish top-two in their Super 8 group and the 2021 champions will progress to the knockout semi-finals.
Travis Head top-scored for Australia with an unbeaten 34 off 17 balls. (AP PHOTO)
"It'll get pretty busy after that game against Scotland. We'll manage as many people as we can over the next few days," Marsh said after Mitch Starc was rested from the Namibia win with calf soreness.
Prior to the clash at Sir Vivian Richards Stadium, the lowest total a team had posted against Australia in a T20I was 73, by Bangladesh at the 2021 edition of the tournament.
But Namibia fell to 3-17 at the end of the powerplay and were in damage control thereafter, with only captain Gerhard Erasmus (36 from 43 deliveries) able to make a start.
Player of the match for a second game running, spinner Zampa became the first Australian man to reach 100 T20I wickets when he bowled Bernard Scholtz for a second-ball duck with the last delivery of his spell.
It came after the 32-year-old trapped wicketkeeper Zane Green (one) lbw and enticed David Wiese (one) into finding Josh Hazlewood in the deep to leave Namibia in all sorts at 6-31.
It was ever-precise paceman Hazlewood (2-18) who had set carnage in motion during the powerplay as Namibia lost 3-1 in the space of 10 balls.
Openers Niko Davin (two from seven balls) and Michael van Lingen (10 off 10) both swatted Hazlewood deliveries to Glenn Maxwell at backward point, with Jan Frylinck (one) joining them in the dugout as Pat Cummins (1-16) began his spell with a wicket maiden.
When Namibia's saviour Erasmus skied Marcus Stoinis (2-9) to Maxwell, Namibia were all but finished at 9-72 and the Australian allrounder had a fourth catch - the equal-most by one player in a World Cup innings.
Victory appeared a formality for the Australians from there after they bowled Namibia out in the 17th over.
Captain Mitch Marsh (19no off nine balls) wasted little time and belted the winning runs. (AP PHOTO)
A feverish David Warner (20) made a fast start by belting Wiese for three consecutive boundaries in the second over, only to hit the paceman's next ball to Ruben Tempelmann at mid-off.
Having narrowly survived a run-out attempt in the first over, Head picked up where Warner left off, his seven boundaries for the night only one short of the entire Namibian team's total for that stat.
Marsh clubbed teenage quick Jack Brassell for 14 runs across the first four balls of the sixth over, ending things in style.
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