|The match was all square at 12-12 until Williams stole the ball from 50 metres out and scored a breakaway try [GETTY]
Replacement centre Scott Williams scored a breakaway try five minutes from time to give Wales a thrilling 19-12 victory over a fired-up England at Twickenham on Saturday to secure their 20th Six Nations Triple Crown.
An inexperienced England side had looked set to upset the odds and secure their own third win of the championship as they led for most of the second half before Williams, on as a second-half replacement for Jamie Roberts, turned the ball over and ran 50 metres to score the only try of the match.
Four penalties each by Owen Farrell, in his first start as England flyhalf, and Leigh Halfpenny had the game beautifully balanced at 12-12 going into the final 10 minutes.
Williams then made the vital score, though Wales had a nervous wait when the video official ruled that David Strettle had failed to ground the ball as he dived over the line in stoppage time.
The win was only Wales' second in 14 attempts at Twickenham spanning 22 years and after their victories over Ireland and Scotland sets them up for a potential championship and grand slam decider at home to France on March 17.
"It's quite unbelievable really, I don't know what to say," Williams said in an on-pitch interview.
"I thought our defence was superb today, England threw everything at us, it was tough but we stuck in there and managed to get the win."
It was England's first defeat under caretaker coach Stuart Lancaster but his inexperienced side showed enough confidence and attacking panache to send their fans into the night confident of good things ahead.
England spent most of the first 20 minutes on the defensive and could have fallen behind inside the first minute only for Strettle to tap tackle George North as the marauding wing sensed a sensational start.
However, they absorbed everything Wales threw at them as, just as in their away wins over Scotland and Italy, their defence was superb, and eventually wrenched control.
Centre Manu Tuilagi, in his first appearance since the World Cup, added the attacking punch that England had been desperately missing in their first two games and only a superb tackle by Welsh captain Sam Warbuton prevented him crossing the line after half an hour.
Farrell, looking relaxed and confident, tried a couple of chipped kick and chases to get the crowd on the edge of their seats but North flattened him with a thunderous hit.
The 20-year-old was as assured in his goalkicking, landing three penalties to two from Halfpenny to give England a 9-6 halftime lead.
Wales lost destructive centre Jamie Roberts at half-time but though Farrell slotted another penalty they did well to survive 10 minutes with Rhys Priestland in the sin bin when they got back to 12-9 with another Halfpenny three pointer.
Halfpenny levelled it with his fourth penalty to set up a thrilling finale after Williams looked to have blown his moment when he ignored a two-man overlap and was wrapped up.
However, he ended the game as the toast of Wales when he wrestled the ball from the grip of replacement lock Courtney Lawes, kicked ahead and re-gathered to score the decisive try, which Halfpenny converted.
England still had time to hit back though and when they swung the ball wide Strettle dived over the line and a mass of red shirts quarter-back-style.
The crowd willed the referee to award the try but the video official ruled he had been held up and Wales took the glory.