England Under-20s saw their Grand Slam dreams crumble against a determined Wales side who ran out 23-13 winners at Cardiff Arms Park.
The result also meant France clinched the Six Nations title for the first time since 2018 after their bonus-point victory over Scotland.
And as much as this was a disappointing evening for England, they were met by a charged up Welsh outfit who were superb in defence and clinical when given the opportunity.
Scores either side of the break from Steffan Emanuel and wing Harry Rees-Weldon shifted the momentum towards the hosts as England failed to add Ralph McEachran's first-half try and eight points from the boot of Ben Coen.
Handling errors proved to be England's kryptonite as time and time again, they coughed up possession but after just two minutes, Mark Mapletoft's side looked like their usual, ruthless selves.
Kepu Tuipulotu - again a standout performer for England - charged through two tackles before delivering a gorgeous offload to McEachran, the Sale Sharks youngster - who has spent time on loan at Lymm in National Two North this season - finishing off the first try.
England continued to turn the screw and when Ospreys lock Dan Gemine was sin-binned for a debatable yellow card shown by referee Griffin Colby, Kane James and then George Timmins went extremely close to extending their lead.
And the current World Under-20 champions would rue those near misses as Wales started to work their way back into the contest after soaking up early pressure.
?? That Steffan Emanuel try ??#SixNationsU20 #WALvENG pic.twitter.com/jb82Iabkew
— Welsh Rugby Union ?????????????? (@WelshRugbyUnion) March 14, 2025
Harri Wilde and Coen exchanged two penalties apiece before Emanuel collected a lovely chip through from Wilde to race over for 13-13.
A fired-up Wales began to grab the game by the scruff of the neck as Rees-Weldon finished superbly in the corner to hand the hosts the lead, which was backed up by a pinpoint touchline conversion from Wilde.
Despite the seemingly calm demeanour of England boss Mapletoft, the alarm bells were starting to ring as Wales' staunch defence continued to force errors from the Grand Slam-chasing visitors.
With a raucous Cardiff Arms Park crowd behind them, Wales fly-half Wilde kicked a third successful penalty on 69 minutes to extend the lead to 10 points.
From here, England needed a miracle but Wales' defence - led by Hartpury University's Harry Beddall and player of the match Harry Thomas - shut out the away side as Richard Whiffin's troops recorded a famous win.
Wales: Bowen; Rees-Weldon, Roberts, S Emanuel, Boshoff; Wilde, Davies; I Emanuel, Thomas, Scott, Jenkins, Gemine, Gwynne, Beddall (capt).
Replacements: Wood, Trevett, O James, Evans, C James, Edwards, Price, Woods.
England: Pearson; Bracken, Hall, Allison, Kinder; Coen, Hanson; McEachran, Tuipulotu, Raymont, Sodeke, Burrow (capt), Kpoku, Timmins, James.
Replacements: Gulley, Scola, Maka, Ainsworth-Cave, Treacey, Davis, Bellamy, Lilley.