This was just about as clinical as it gets from Australia as, following their 50-over World Cup triumph in India last year, they continued their bid to become double world champions.
Left-arm pace bowler Mitchell Starc was rested but that did not stop them seizing control of the match in the opening powerplay.
Two wickets for Hazlewood and one for Pat Cummins left Namibia 17-3 after six overs, while skipper Gerhard Erasmus took 17 balls to get off the mark.
Erasmus recovered to make a 43-ball 36 but found no support as the Australia bowlers relentlessly tore through the middle and lower order.
Zampa was at the heart of it and a lovely googly to bowl Bernard Scholtz gave him his fourth wicket of the game and his 100th in T20Is.
The 32-year-old is the first men’s player to reach the landmark for Australia and third overall after Ellyse Perry and Megan Schutt.
Once Stoinis wrapped up the innings, it was over to the batters and they were in no mood to hang around.
David Warner had 20 from his first seven balls before falling to David Wiese in the second over.
Head and Marsh took up the mantle and, after 11 fours and four sixes, Australia finished the job with 86 balls to spare.
England will likely need to show similar ruthlessness in their next two games if they are to join Australia in the Super 8s.
If not, they may be reliant on a repeat performance from Marsh’s team against Scotland.
