Norman Vanua's six-hitting heroics took Papua New Guinea to a thrilling and unexpected two-wickets victory over Ireland at Stormont.

Chasing 124, PNG had stumbled to 93 for 8 and then needed 27 off the last 14 balls before Vanua launched a stunning attack on the Irish bowlers.

The fifth ball of the eighteenth over, bowled by Alex Cusack, was flicked into the wall of the Civil Service pavilion before a single gave Vanua the strike for the penultimate over.

Delivered by John Mooney - Ireland's best player in the tournament so far - the first ball disappeared over deep square-leg, two singles followed, and with 12 needed from 9, the fourth and fifth balls of Mooney's over were belted high over the leg-side boundary to spark scenes of jubilation among the PNG players and staff.

Until this late derring-do, the PNG batting display had been abject: four batsmen were caught on the ropes between long-on and deep square-leg, none of the top order appeared capable of manipulating the bowling, and the required rate rose higher and higher as wickets fell.

Kevin O'Brien was the pick of the Irish bowlers, taking 2 for 11 from his four overs, and until the last act Porterfield's men had produced another impressive and professional display in the field, a performance that looked - for all the world - to have secured another two points.

Earlier in the day, having chosen to bat first in helpful bowling conditions, the Irish had their captain to thank for making as many as 123-9.

The left-hander, who finished unbeaten on 57 (58 balls, 4 fours and 1 six) was the only member of the Irish top order to come to terms with the slowness of the pitch and the moving ball.

Paul Stirling, Andy Balbirnie, and Niall O'Brien all were bowled, while some dubious running between the wickets accounted for Stuart Thompson and George Dockrell.

The four PNG seamers, bowling at nothing more than medium-pace, had been penetrative and accurate, the best of the being Willie Gavera, who recorded figures of 3-17 from his four overs.

A late flurry from Alex Cusack (13*), who struck a four and a six in the four deliveries he faced, helped lift the Irish to 123 from their twenty overs and, for a long time, this seemed like it would be enough. Norman Vanua, however, had other ideas.

Victory today would have all but secured top spot in Group A for the Irish, who next take on Hong Kong at Malahide on Friday afternoon. Papua New Guinea, meanwhile, have consolidated second place and now look certain to qualify for the tournament's play-off stage.