Ireland 12 (6)
Wing Shane Williams dives over to equal the Wales try-scoring record
Pens: O'Gara 4
Wales 16 (3)
Tries: S Williams
Cons: S Jones
Pens: S Jones 2, Hook
Wales sealed the Triple Crown and kept their Grand Slam dreams alive with a hard-fought win over Ireland in Dublin.
Ronan O'Gara's kicks gave Ireland a 6-3 half-time lead, while Shane Horgan was stopped inches short of the line.
Despite having two players sin-binned, Wales dominated the second half with Shane Williams's record-equalling 40th Test try putting his side ahead.
Ireland closed to within a point, but James Hook's late penalty sealed a famous win for Warren Gatland's side.
The result will see the level of expectation in Wales soar even higher with next Saturday's match against France turning into a Grand Slam decider.
Much of that expectation will fall on the slim shoulders of winger Williams, with the Ospreys man equalling Gareth Thomas's Welsh record with his 40th Test try and turning in a man-of-the-match performance.
Ireland started solidly, with full-back Rob Kearney returning a long punt from Lee Byrne with a confident run and forcing Wales to concede a penalty for not rolling away.
The home side kicked for touch to give Ireland an attacking line-out on the Welsh 22 and when Wales stole the ball illegally, O'Gara stepped up to put Ireland ahead.
Ireland conceded a penalty almost in front of their posts as John Hayes buckled in the scrum but Wales fly-half Stephen Jones, not helped by a swirling wind, somehow missed.
Spurred by some darting runs from scrum-half by Eoin Reddan, Ireland worked their way back upfield and Wales again gave up the penalty for O'Gara to score.
The Munster fly-half was also on form with his tactical kicks and the two Wales wings, Mark Jones and Shane Williams, were turned at regular intervals.
Ireland wing Shane Horgan was stopped just short of the try line
Capitalising on the pressure, Horgan surged to within inches of the line before a magnificent Mike Phillips tackle stopped him just short.
Wales rallied with a series of drives that earned fly-half Jones a second pot at the posts, and this time he made no mistake.
Jones missed a more difficult kick as the game ticked over the half-hour mark.
But Wales were starting to motor with a break involving the superb Gavin Henson, Shane Williams and Tom Shanklin putting Lee Byrne into space, clear only for Kearney to snuff out the danger.
Ireland's defence was working overtime but the line held firm for a good five minutes but the pressure eventually told and a penalty was conceded.
But a loss of discipline from scrum-half Mike Phillips proved costly as he dropped a knee into the ribs of the prone Marcus Horan, as the prop refused to release the ball.
Phillips earned a trip to the sin-bin and cost his team the chance to level the scores before half-time.
Wales kept their composure though, showing impressive patience immediately after the restart to make light of their man disadvantage and Stephen Jones kicked a penalty to level the scores.
The hwyl was flowing for Wales and Shane Williams took advantage to score a trademark try as he spotted half a gap, handed-off a poor attempted tackle from Andrew Trimble and darted over.
Ireland captain Brian O'Driscoll tackles rival centre Gavin Henson
Stephen Jones added a superb touchline conversion from the right and suddenly Wales were in control with a 13-6 lead.
The returning Phillips, desperate to make amends, burst through the midfield to set up another dangerous attack, but Wales wasted an overlap.
Ireland number eight Jamie Heaslip burst through a gap, but the support suddenly vanished - not surprisingly with Martyn Williams taking out Eoin Reddan with a trip.
The offence was spotted and the flanker became the second Wales player to visit the sin-bin.
O'Gara punished the indiscretion with two penalties in quick succession to put Ireland within a point with 12 minutes to go.
But hopes of a Ireland victory were effectively ended by a brainless penalty conceded by Ireland substitute Bernard Jackman as the hooker clattered Wales skipper Ryan Jones - who was nowhere near the ball - in the back right under the nose of the referee.
The penalty chance to put Wales four points clear and replacement James Hook held his nerve to cap a fine Wales fightback.
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Ireland: R Kearney (Leinster); S Horgan (Leinster), B O'Driscoll (Leinster, capt), A Trimble (Ulster), T Bowe (Ulster); R O'Gara (Munster), E Reddan (Wasps); M Horan (Munster), R Best (Ulster), J Hayes (Munster), D O'Callaghan (Munster), P O'Connell (Munster), D Leamy (Munster), D Wallace (Munster), J Heaslip (Leinster).
Replacements: B Jackman (Leinster) for Best (71), T Buckley (Munster) for Hayes (71), M O'Driscoll (Munster), S Easterby (Scarlets), P Stringer (Munster), P Wallace (Ulster), L Fitzgerald (Leinster) for B. O'Driscoll (71).
Wales: L Byrne (Ospreys); M Jones (Scarlets), T Shanklin (Blues), G Henson (Ospreys), S Williams (Ospreys); S Jones (Scarlets), M Phillips (Ospreys); G Jenkins (Blues), M Rees (Scarlets), A Jones (Ospreys), I Gough (Ospreys), AW Jones (Ospreys), J Thomas (Ospreys), M Williams (Blues), R Jones (Ospreys, capt).
Replacements: G Williams (Blues), D Jones (Ospreys) for A. Jones (72), I Evans (Ospreys), G Delve (Gloucester) for R. Jones (75), D Peel (Scarlets), J Hook (Ospreys) for S. Jones (65), S Parker (Ospreys).
Sin-bin: Phillips (39), M. Williams (62).
Referee: Wayne Barnes (England).