A stunning opening burst from seamer Ruben Trumpelmann and an unbeaten 32 by JJ Smit down the order helped Namibia secure a nervy four-wicket win over Scotland in their Group I encounter in Abu Dhabi on Wednesday.
Set a modest 110 for victory, Namibia made heavy weather of the chase, losing wickets at key moments on a tricky pitch before Smit and David Wiese (16) did just enough to get them over the line with five balls to spare.
It was Scotland's second straight defeat following their crushing loss to Afghanistan on Monday, effectively ending their hopes of making the semi-finals with New Zealand, India and Pakistan still to come.
"Delighted to get another World Cup win, we were emotional coming from the first group and we managed to put in another good performance... with that score we had a clear gameplan and luckily with two partnerships we got home," said Namibia captain Gerhard Erasmus.
Scotland could never really recover after left-arm quick Trumpelmann (3-17) ripped their top-order with three wickets in the first over of the innings. Wiese (1-22) later removed Craig Wallace (4) as Scotland ended the powerplay on 22-4.
"I was nervous out there, but I thought, it's the World Cup, so why not enjoy it. I use swing as a weapon up front, so luckily it went my way today. We hope to win a few more, but this is massive for us," said Trumpelmann, who was named player of the match.
Erasmus added: "Ruben sets high standards. By his own admission he hasn't hit the straps but very delighted that he came out here and executed. That allowed us to start well and throw the first punch."
Michael Leask (44) briefly threatened to salvage the innings but had his stumps rattled by Smit (1-20) just as he was preparing to mount a late assault before Chris Greaves (25) made sure that Scotland crossed the 100-run mark, finishing on 109-8.
Scotland skipper Richard Berrington rued the lack of partnerships after their shocking start, saying that they were 20-30 runs short.
"I thought Leask and (Matthew) Cross played well. 120 would have given us a better chance. It was important we put the Afghanistan game behind us. We were confident today but we didn't execute," he said.
Namibia next face Afghanistan in Abu Dhabi on Sunday, while Scotland take on New Zealand in Dubai on November 3.