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
The scorers:
For England:
Pens: Farrell 4
For Wales:
Try: S. Williams
Con: Halfpenny
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.
Venue: Twickenham
Referee: Steve Walsh (Australia)
Assistant referees: Peter Fitzgibbon (Ireland), Pascal Gauzere (France)
TMO: Iain Ramage (Scotland)
The scores were locked at 3-3 at half-time but a fifteen-minute spell early in the second period saw Wales score three tries to build an unassailable lead.
Italy outscored their hosts two tries to one, however it was once again the boot of Owen Farrell that saved the day for England as the young centre contributed 14 points in horrendous conditions.
Revenge was on the menu for Ireland following their World Cup exit against the Welsh, but defeat is what they were served at the Aviva Stadium where they have now lost three games on the trot.
Philippe Saint-André's team ran four tries past their visitors for a comfortable win although the scoreboard belies the quality of the Italian performance.
Stuart Lancaster's new-look team claimed England's first win in the Scottish capital since 2004 but the result had less to do with a new-era of creativity that English fans had been hoping for than the hosts' inability to convert their chances into points.
The result made it four wins in a row for Australia over Wales, as they backed up their victory when the teams last met in the RWC bronze final, and extended the hosts' poor record against the Tri-Nations to just one success in sixteen Tests.
As expected, running rugby was the order of the day but in the end the Wallabies were more clinical in the execution of their moves and were rewarded with eight tries against the men in black and white hoops.
Les Bleus were a completely different side to the one that had fallen to the 2011 hosts and also Tonga during the Pool stages. And they pushed the Kiwis right up until the death in a highly-charged 80 minutes at Eden Park on Sunday.
Both sides crossed the whitewash twice, with Wales bagging a consolation second try on full-time to end the match -- but not the tournament -- on a high note.
The hosts -- the only unbeaten team left in the tournament -- will face France at the same venue in seven days in a repeat of the 1987 RWC final.
Did they deserve it for the way they played against fourteen men? No. But that is rugby as Wales bow out following what was a superb tournament.
The All Blacks were far from their best but teams seldom are in knockout rugby. What may be a concern to them though was the loss of Colin Slade to injury. Dan Carter's fly-half replacement left the field during the first stanza with a leg injury, being replaced by third-choice Aaron Cruden.
The Wallabies scored the only try of the game but needed a late James O'Connor penalty to scrape past the dominant Springboks.
England were second best as they could not make it three finals in a row, while les Bleus deservedly march on to face Wales next week.
In what was a breathless encounter in the New Zealand capital, the Welsh outscored Ireland by three tries to one to seal a semi-final spot on rugby's biggest stage for the first time since 1987.
There was little to separate the two nations at the break with three Ronan O'Gara penalties edging Mirco Bergamasco's two. But after their rest, the Irish stepped up through the gears in Dunedin.
Wales secured a four-try bonus point in the first half of a one-sided affair and will now face either Australia or Ireland in Wellington next Saturday.