Northern Ireland's dreams of Victory Shield glory were crushed by some classy finishing from a slick Wales side.
A 1-0 win over England a fortnight ago gave Desi Curry's under-16s a chance of winning the tournament for the first time since 2000.
Needing a win to put pressure on Scotland ahead of the final game next week, Northern Ireland went down 4-0 to the Welsh and they will now finish bottom of the group rather than on top.
Wales claimed their first success in this season's tournament with two goals in the opening 20 minutes and two more in the space of 25 minutes in the second-half.
Northern Ireland were rocked when the Welsh grabbed the lead after only five minutes.
Tyler Roberts picked up a throw in on the right wing and slipped the ball to Nathan Broadhead. He ran at the Northern Ireland defence, took the ball past Matthew Smyth and Dylan King fired his shot into the top corner of the net from just inside the box.
The Northern Ireland youngsters were struggling to break down the Wales defence and when Michael Kerr made a break down the right wing in the 14th minute, his progress was well blocked on the edge of the box.
Two minutes later Ryan Caulfield registered Northern Ireland's first shot on goal, but it failed to trouble the Wales goalkeeper.
Wales doubled their lead on 21 minutes, but they were helped by some sloppy play by the Northern Ireland defence.
King's poor pass was picked up by Broadhead. He sped down the right wing and sent his cross into the box where King failed to cut it out and Liam Cullen tucked the ball into the net.
It was all Wales at this stage and 10 minutes later Joe McNulty's free-kick was flicked on by Cullen and Northern Ireland goalkeeper Conor Hazard was relieved to see the ball fly wide of his goal.
Matthew Henry then forced a corner for Northern Ireland a minute later, but Wales broke immediately and McNulty sent a tame volley to Hazard.
In a whirlwind period of play Shea Conaty – who scored Northern Ireland's winner against England two weeks ago – shot over the bar.
The Portadown striker then shot wide 10 minutes into the second half before Wales struck again with their third within 60 seconds.
Henry lost the ball to Ryan Harrington in midfield, he drove forward and get Roberts who was allowed to turn on the edge of the box and shot home from 10 yards.
The win was sealed when substitute Elijah Chilekwa volleyed a left wing cross back across the face of goal for Roberts to tap the ball home from close range with four minutes to go.
WALES: Absalom, Coxe, Abbruzzese, Leak, Ovenden, Williams, Cullen, McNulty, Roberts, Harrington, Broadhead.
NORTHERN IRELAND: Hazard, Kerr, Mulligan, Smyth, King, Henry, McClean, Crowe, Caulfield, Gordon, Conaty.