The result extended Namibia’s unbeaten record against their neighbours to two matches, following their victory in the first meeting between the sides last year.
While the Proteas batted first on that occasion, this time the Namibians were sent in to bat and the hosts made an excellent start as Jan Frylinck and Louren Steenkamp put on 84 for the first wicket. They raced to 57 without loss during the powerplay before Proteas stand-in captain Bjorn Fortuin broke the partnership in the 10th over, bowling Steenkamp for 41 off 29 balls.
Frylinck continued to attack, reaching 60 from 38 deliveries before falling to part-time spinner Dewald Brevis while attempting a third successive six.
The hosts then lost a bit of momentum, surrendering nine wickets for 79 runs in the second half of their innings. Fortuin finished with 2-17, while Prenelan Subrayen claimed 3-23.
Debutant Duan Jansen struck twice in two balls late in the 19th over as the hosts were restricted to 163-9. The Proteas also suffered an injury concern when Lutho Sipamla left the field midway through his second over with a left hamstring problem.
In response, the visitors' chase quickly unravelled. Jordan Hermann, Lhuan-dre Pretorius and Tony de Zorzi all fell cheaply, leaving the T20 World Cup semi-finalists 39-3 inside seven overs.
Rubin Hermann was then bowled to leave the Proteas 78-4 before Brevis launched a determined counter-attack.
The 22-year-old struck 75 from 50 balls, his second T20I half-century, to give the Proteas hope of completing the chase. However, he was caught at short third man off Ruben Trumpelmann with two overs remaining.
With little support around him, Brevis' dismissal effectively ended the Proteas' hopes and they finished on 145-9.
Trumpelmann led the successful defence with 3-24, while Jansen - brother of Marco - added an unbeaten 25 to cap an impressive debut - a silver lining for the Proteas on an otherwise disastrous day.
The Proteas will look to bounce back when they face Zimbabwe in Windhoek on Saturday.
Duan Jansen took three wickets while Dewald Brevis smashed an unbeaten 72 from 32 balls as the Proteas bounced back from an opening defeat to beat Zimbabwe by seven wickets in the T20 tri-series clash in Windhoek.
Former Proteas captain Dean Elgar has announced his retirement from all forms of cricket following the conclusion of the 2026 County Cricket season.
Veteran leg-spinner Graeme Cremer has been recalled to Zimbabwe's T20I squad for the upcoming tri-series against South Africa and Namibia, with Sikandar Raza named captain of the 15-man squad.
Namibia have named a 16-man squad blending experience and youth for the inaugural T20I tri-series against South Africa and Zimbabwe in Windhoek from August 28 to September 6.
