Ireland batsmen's inadequacies to face quality seam or spin were exposed on the Grenada National Stadium track on which Sri Lanka bowlers strode like lions.
It was a sad end to Ireland's World Cup party as their batting collapsed like a pack of cards after their openers put up 28 for the first wicket. Five of their batsmen failed to score and only three could cross the double figure.
Mahela Jayawardene's decision to put Ireland in was justified by his bowlers but none had anticipated such a poor showing by the debutants.
Jeremy Bray and William Porterfield added 28 runs in 7.3 overs before Mahroof struck.
Bray hit the Sri Lnkan pacer for two successive boundaries but when he tried to hit another one miscued the shot and was superbly caught by Russel Arnold. He top-scored for his side with 20 runs (29 balls, 4X4), and then the collapse started.
Mahroof got rid of two more batsmen off his fifth and sixth balls to reduce the Irish to 28 for 3.
An 18-run fourth wicket partnership between Porterfield and Niall O'Brien took the score to 46 when Murali was brought into the attack and the spin magician spun such a web around the Irish batsmen that they just could not break out of it.
But for Longford-Smith's 18 (21 balls, 2x4, 1X6), Ireland would have been in much worst conditions.
Murali took four for 19 off five overs and Mahroof scalped four for 25 off his ten overs.
Prior to this match the lowest total in this World Cup was in the name of Bermuda (78) that too against Sri Lanka in a preliminary league match.