Sri Lanka chased down the target of 172 with seven balls to spare at the Sharjah Cricket Stadium.
Lahiru Kumara and spinners combine as ruthless Sri Lanka thump clueless Netherlands.
Sri Lanka qualified for the Super 12s stage of the T20 World Cup with a 70-run win over Ireland in Abu Dhabi.
Three wickets from Theekshana wrapped up Namibia for 96.
Openers de Kock and Hendricks made unbeaten half-centuries in a comprehensive 10-wicket win.
Sri Lanka have named four spinners in their 15-man squad for the T20 World Cup starting next month.