A solo try from Scott Williams in the 76th-minute handed Wales a 19-12 Six Nations victory over England at Twickenham on Saturday and with it the Triple Crown.
The replacement back's breakaway try at the death put Wales into the lead for the first time in an enthralling battle after England had led 9-6 at half-time.
There was tension right up to the final whistle however as England wing David Strettle crossed after the final hooter but television match official Iain Ramage adjudged there to be insufficient evidence that he managed to ground the ball.
While Stuart Lancaster's team will be bitterly disappointed by the narrow defeat, the young side can take encouragement from their best performance of this year's Six Nations.
Wales meanwhile remain on course for the Grand Slam, with home games against Italy and France still to play.
Wales did most of the early playing but England opened the scoring in the 24th minute when Owen Farrell split the uprights. It took Wales less than two minutes to reply as Leigh Halfpenny landed his second attempt at goal to level the scores.
After a slow start England were growing in confidence and looking dangerous. A brilliant tackle from Sam Warburton denied Manu Tuilagi a try but Farrell was able to restore the hosts' lead with another penalty around the half-hour mark.
A beautiful strike from long range by Halfpenny drew Wales level once again as the game began to grow in pace and the big hits continued to rain down.
England would head into the changing rooms in front however as Farrell made it three-from-three on the stroke of half time.
The second period started terribly for Wales as Rhys Priestland was charged down and then shown a yellow card as he tried to make amends by preventing an England try by jumping the gun at the breakdown on his own try-line.
Farrell duly added three more but Halfpenny restored the status quo before Priestland's time in the sin-bin had been served.
Farrell missed his fifth attempt at goal before being limping off to be replaced by Toby Flood but Halfpenny was on target with nine minutes left on the clock to leave the scores locked at 12-12.
Williams then turned match-winner, ripping the ball off Courtney Lawes and chasing down his own kick to score, before Strettle was denied at the death.
Man of the match: There are a number of candidates with Owen Farrell belying his young age with another cool performance. Manu Tuilagi made an impressive return to the English midfield but Wales skipper Sam Warburton gets the nod after a top show. A try-saving tackle on Tuilagi in the first half was just one of countless hits.
Moment of the match: The 81st minute. David Strettle dives over. He is rolled over by Jonathan Davies and tries to ground the ball behind his head before it is pushed back over to the wrong side of the line. Does it graze the surface? The TMO looks at it from every possible angle. It could go either way. Twickenham waits...in vain.
Villain of the match: N/A
Pens: Farrell 4
Try: S. Williams
Pens: Halfpenny 4
Yellow card: Priestland (Wales - 45th min - professional foul)
England: 15 Ben Foden, 14 Chris Ashton, 13 Manusamoa Tuilagi, 12 Brad Barritt, 11 David Strettle, 10 Owen Farrell, 9 Lee Dickson, 8 Ben Morgan, 7 Chris Robshaw (capt), 6 Tom Croft, 5 Geoff Parling, 4 Mouritz Botha, 3 Dan Cole, 2 Dylan Hartley, 1 Alex Corbisiero.
Replacements: 16 Rob Webber, 17 Matt Stevens, 18 Courtney Lawes, 19 Phil Dowson, 20 Ben Youngs, 21 Toby Flood, 22 Mike Brown.
Wales: 15 Leigh Halfpenny, 14 Alex Cuthbert, 13 Jonathan Davies, 12 Jamie Roberts, 11 George North, 10 Rhys Priestland, 9 Mike Phillips, 8 Toby Faletau, 7 Sam Warburton (capt), 6 Dan Lydiate, 5 Ian Evans, 4 Alun-Wyn Jones, 3 Adam Jones, 2 Ken Owens, 1 Gethin Jenkins.
Replacements: 16 Richard Hibbard, 17 Paul James, 18 Ryan Jones, 19 Justin Tipuric, 20 Lloyd Williams, 21 James Hook, 22 Scott Williams.
Referee: Steve Walsh (Australia)
Assistant referees: Peter Fitzgibbon (Ireland), Pascal Gauzere (France)
TMO: Iain Ramage (Scotland)