Oman pulled off a shock two-wicket victory in their first game at a major tournament to strike a blow to Ireland's hopes of qualifying for the World Twenty20 Super 10 stage.
An experienced Ireland side were expected to start the tournament with a win in Dharamsala on Wednesday, but Oman announced themselves on the world stage with a dramatic final-over triumph in Group A.
Gary Wilson top scored with 38 as Ireland posted 154-5 after captain Will Porterfield won the toss and elected to bat first, with Munis Ansari taking 3-37.
Zeeshan Maqsood (38), who earlier produced a stunning catch to dismiss Paul Stirling, and Khawar Ali (34) combined for an opening stand of 69 but an Oman collapse looked to have swung the game back in Ireland's favour.
However, Aamer Ali (32) kept the underdogs in it and the Oman players charged onto the pitch to celebrate victory with two balls to spare when a Max Sorensen delivery went through wicketkeeper Niall O'Brien's legs for four.
A magnificent one-handed diving catch from Maqsood to get rid of the dangerous Stirling (29) was the highlight of an Ireland innings which included only two sixes.
Maqsood and Khawar got Oman off to a flier in their run chase - the latter striking two towering sixes - before Kevin O'Brien (2-25) sent them both on their way in quick succession.
Andy McBrine (2-15) and Sorensen (2-29) did further damage, leaving Oman needing 14 to win off the last over and some wayward bowling from Sorensen enabled them to claim a historic win which ensured they join Bangladesh on two points.