BackSri Lanka Women win by 10 wickets
Sri Lanka won the toss and opted to field first, with Ireland managing just 105-9 in their 20 overs.
Amy Hunter, who was named vice-captain for the tournament in the absence of Orla Prendergast, was first up for Ireland and managed 21 runs, including three fours, before she was dismissed by Sathy Sandeepani.
Captain Gaby Lewis exited for just four runs while Lara Maritz, making her first appearance since 2021, registered 13 before Kavisha Dilhari got her out.
Louise Little was then ran out by Nilakshi de Silva after recording Ireland's highest individual total of 28.
Laura Delaney added 15 runs before she exited in the same over as Little, while debutant Abi Harrison managed 13 not out to take Ireland close to a century.
They did manage to edge over 100, but Cara Murray, Jane Maguire and Kia McCartney were all swiftly dismissed in the last three overs to leave Sri Lanka in a strong position.
The unbeaten partnership of Vishmi Gunaratne and Hasini Perera helped them surpass the target in just 13 overs.
Gunaratne registered 53 from 37 balls including six fours and one six, while Perera managed the same tally from 41 balls with eight fours and a six, as Sri Lanka claimed a comfortable victory.
Lloyd Tennant's side will now turn their attention to Friday's next group game against UAE [05:00 GMT].
Ireland will also face Papua New Guinea [Monday, 16 November] and Scotland [Wednesday, 18 November] in the group stage.