World Twenty20 newcomers Oman stunned Ireland with a two-wicket victory with two balls to spare in their first game.
Chasing 155, Oman openers Zeeshan Maqsood and Khawar Ali added 69 and, after a collapse of 4-21, Aamer Ali hit 32 from 17 balls in Dharamsala.
With 14 needed from the final over, Max Sorensen bowled two no-balls, one of which went for four and another which went for four byes to end the match.
Earlier, pace bowler Munis Ansari took 3-37 as Ireland made 154-5.
Ireland, playing in their sixth World T20 and used to causing upsets, were given a taste of their own medicine by the lowest-ranked team in the tournament.
Ireland must now beat Bangladesh and the Netherlands to have any hope of topping Group A and claiming one of the two places available in the main draw.