Ireland 225 for 9 (Porterfield 62, Haq 3-26) beat Scotland 223 for 9 (Mommsen 91*, Dockrell 4-24) by one wicket
Scorecard and ball-by-ball details
Three days after a brilliant spell of bowling nearly shocked England in Malahide, Tim Murtagh delivered with the bat to serve a big blow to Scotland's chances of qualifying for the 2015 World Cup.
Murtagh slugged a six and a four when nine were needed from three balls to squeeze Ireland home for a one-wicket victory in Belfast. The defeat means Scotland cannot now finish in the top two of the World Cricket League Championship and must now wait for the qualifying tournament for the chance to book a place in Australia and New Zealand.
Having made 269 for 7 against England earlier in the week, Ireland were fancied to chase 224 but their middle order stumbled badly after a bright start. Murtagh arrived at the wicket with 15 needed from nine balls but he and George Dockrell could only manage singles from the next six deliveries.
But with boundaries required, Murtagh found his touch and blasted left-arm seamer Rob Taylor over long-off for six to leave three needed in two balls. He put the next delivery through point to seal victory.
Ireland had been in big trouble. William Porterfield continued his excellent form with a half-century and added 95 for the first wicket with Paul Stirling to put the pursuit on course. But they then coughed up four wickets for 17 runs in six overs as Majid Haq's offspin picked up three wickets.
Finally Trent Johnston and Max Sorensen settled things and got the chase moving again with six boundaries between them but Johnston fell with 44 still remaining. Sorensen and Murtagh managed to bring the requirement down to 17 from the final two overs but Sorensen fell trying to swing Machan out of the ground. The requirement looked beyond Ireland until Murtagh's late hitting.
It was a bitter disappointment for Scotland who had looked on course to take the first game in the two-match series, which will be followed by a four-day Intercontinental Cup game. Preston Mommsen's unbeaten 91 gave them a solid total.
He was by far the standout performance of the Scotland innings. His 122-ball stay included 10 fours and held the innings together. The next highest score was 27 as they failed to find significant partnerships. Matt Machan made that second-top score from only 25 balls but more was asked of him in the absence of Kyle Coezter.
George Dockrell tore through the middle order, finishing with 4 for 24 as Scotland were kept well within range. But Safyaan Sharif's late burst of 26 in 25 balls bumped Scotland up to a competitive total.