Put in, Ireland posted 225/8 in 50 overs, and importantly kept their opponents in the field under a mostly scorching sun for the duration of the innings.
Jamie Grassi set things up with a 60-ball 32 before skipper Harry Tector consolidated with a 62-ball 36 and Graham Kennedy attacked in the death overs, his unbeaten 24-ball 37 bolstering the total.
In reply, Afghanistan couldn't really put on a partnership that took it away from Ireland, who kept picking up important wickets.
With four balls remaining, Max Neville had Qais Ahmed dismissed, and Ireland clinched the match, bowling out Afghanistan for 221.
In other matches played during the day, England rode on centuries from Liam Banks (120) and Will Jacks (102) to thrash minnows Canada by 282 runs and register their second-biggest U-19 ODI victory.
Canada came into this game with hopes of beating England and making the Super League quarter-finals, but those were effectively ended after they conceded what was their highest-ever total of 383/7 in an U-19 ODI, and confirmed after they were bowled out for 101.
Canada slipped to 20/4 in less than seven overs into their chase before crawling to 75/5, but in the end England were just too good, each of their first four bowlers taking at least two wickets, giving the minnows no respite.
In another tie, the West Indies rode on a superb ton from Alick Athanaze (116 not out) before Bhaskar Yadram (5/18) and Jeavor Royal (4/25) rammed home their advantage, securing victory over Kenya by 222 runs.
The final match of the day witnessed hosts New Zealand continue their unbeaten run in the tournament, beating South Africa by 71 runs.
Electing to bat, New Zealand rode on Rachin Ravindra's all-round show, first hitting an 89-ball 76 to help the hosts post 279/8 and then returning 4/32 to bowl South Africa out for 208.
(This story has not been edited by Social News XYZ staff and is auto-generated from a syndicated feed.)
