Scotland head coach Shane Burger was disappointed his side lost against Namibia, in a game they were in control of.
Despite only posting a modest total of 208 from their 50 overs, Scotland had the hosts at 111 for seven in reply but failed to see the job through.
The Scots had won their first two games on this tour, including the opening tie against Namibia four days ago, but will see this as a missed opportunity.
“We’re very disappointed in the end result,” said Burger. “Credit to the partnership at the end there that Namibia put together. It showed a real fight and spirit in the way they played.
“An opposition team can outplay you and you can accept that but in this case, we allowed them to play like they did which is disappointing.
“I don’t think we can look away from what Brandon McMullen did in just his third international. He delivered with bat and ball and took an excellent catch.
“With bat in hand, no-one really capitalised on a start. There were a few cameos here and there but we didn’t have that big partnership to get us 250-plus, on a wicket we thought was good to bat on and should have got harder and harder throughout the day.”
Scotland struggled to get their innings going. They lost Kyle Coetzer with the first ball of the match and Chris McBride five overs later.
George Munsey got to 50 but both he and Richie Berrington were gone before the mid-way point, with Scotland restricted to 85 for four.
Brandon McMullen (56) came to the fore again with the bat but with Matthew Cross and Mark Watt falling cheaply, there was limited support around him.
Tail-enders Safyaan Sharif and Chris Sole helped nudge the Scots to 208 all out.
McMullen picked up where he left off with the ball, removing both openers with just 13 on the board, and took a catch off Mark Watt to remove Namibia captain Gerhard Erasmus.
Watt was the pick of the Scotland bowlers, returning figures of three-for-28, but a partnership of 99 from Jan Nicol Loftie-Eaton (67 not out) and Pikky Ya France (52no) saw Namibia over the line.
“It’s not ideal to lose the match, when we were in total control of it,” said Burger. “That’ll hurt but I suppose the hot conditions took its toll and it was hard to keep the energy up.
“They tried their hardest but the execution wasn’t quite there.”
Scotland still top the World Cricket League 2 group, ahead of facing Nepal on Thursday.