The men flying the star-spangled banner posted a formidable 199/4 before seeing off Nambia’s chase, leaving them floundering on 168/6 under the Chennai lights.
Opting to bat first and put Namibia under pressure, USA openers Monank Patel and Shayan Jahangir did just that. They took USA to 68 in the seventh over before Willem Myburgh deceived Jahangir for 22.
Myburgh got his second when the dangerous Patel holed out at long-on for a sparkling 52 off 30 balls and Saiteja Mukkamalla fell shortly after, but the USA were still rollocking along at 103/3 in the 11th.
Sanjay Krishnamurthi put the ailing Namibia attack to the sword in the final six overs, which yielded 83 runs. He flew to his maiden T20 half-century and would finish not out on 68 off just 33 after firing half a dozen sixes.
In the chase, Namibia were in the hunt up front. Opener Louren Steenkamp was impressive for his 58 from 39 and Namibia were 99/1 after 10.2 overs.
But their chase faded away after the dismissals of Jan Nicol Loftie-Eaton (28) in the 11th over and then Steenkamp when they were looking to accelerate.
South African-born Shadley van Schalkwyk starred with the ball for the USA, picking up the key wickets of Jan Freylink (19) and captain Gerhard Erasmus (6) to finish with 2/30.
Azmatullah Omarzai starred with bat and ball to help Afghanistan register their first win of their T20 World Cup campaign after beating UAE by five wickets with four balls to spare.
Australia have confirmed that Steve Smith has officially been added to their T20 World Cup squad, replacing injured fast bowler Josh Hazlewood.
Pakistan head coach Mike Hesson admits his team "probably took a little step back" in their defeat in the high-stakes T20 World Cup clash against India in Colombo on Sunday.
A sensational 77 off 40 balls from Ishan Kishan propelled India to a commanding 61-run victory over Pakistan in Colombo on Sunday, securing their place in the Super 8s and extending their dominance over their arch-rivals in World Cups to 8-1.
