Sri Lanka beat the Netherlands by 16 runs to reach the T20 World Cup Super 12 stage and the Dutch also qualified after the United Arab Emirates broke Namibia's hearts.

Asia Cup champions Sri Lanka suffered a shock defeat to Namibia in their first game of the tournament, but avoided an early exit by responding with victories over the UAE and Netherlands.

A brilliant knock of 79 from 44 balls by man of the match Kusal Mendis enabled Sri Lanka to post 162-6 at Kardinia Park on Thursday, Charith Asalanka also chipping in with 31.

The Netherlands fell short on 146-9 in reply, spinners Wanindu Hasaranga (3-28) and Maheesh Theekshana (2-32) stepping up when Sri Lanka needed them, with opener Max O'Dowd's unbeaten 71 in vain.

That left the Dutch's fate out of their hands, but UAE came to their rescue by dramatically securing their first T20 World Cup win to knock Namibia out in Geelong.

Muhammad Waseem top scored with 50 and captain Chundangapoyil Rizwan made 43 not out in UAE's 148-3. A victory would have seen Namibia advance with Sri Lanka, but they were beaten by seven runs after being restricted to 141-8.

David Wiese's half-century in a stand of 70 with Ruben Trumpelmann looked to have put Namibia on course to qualify, but he was out 55 in an excellent final over from Waseem

Group A winners Sri Lanka face the runners-up in Group B in their Super 12 opener at Bellerive Oval on Sunday, while the Netherlands face Bangladesh at the same venue in Hobart a day later.