Early scores from Brian O’Driscoll and Ronan O’Gara set Ireland on the right road at the Millennium Stadium, but Wales held the visitors scoreless in the second half to take a 19-13 victory.
Brian O’Driscoll’s third-minute try, which saw him equal Ian Smith’s Championship record of 24 tries, got Ireland off to an ideal start in the Cardiff cauldron.
Ronan O’Gara’s conversion took his Irish points record to the magical figure of 1000 and two penalties from the Corkman, the second on the stroke of half-time, gave his side a 13-9 lead.
But a controversial 50th minute try from scrum half Mike Phillips, which was converted by James Hook, edged the Welsh ahead for the first time.
Hook, who was named RBS man-of-the-match, added his third penalty of the evening to extend the lead to 19-13 and try as they might, Ireland had no answer in another tense finale at the Millennium Stadium.
O’Driscoll and his team-mates were left ruing the concession of that Phillips try which saw came after Wales captain Matthew Rees took a quick lineout throw and caught Ireland off guard.
However, Rees’ quick throw was taken with a different ball from the one that was sliced into touch by Ireland replacement Jonathan Sexton, which is against law 19.2 of rugby’s rulebook.
Referee Jonathan Kaplan consulted Scottish assistant official Peter Allan before awarding the score, but O’Driscoll and Paul O’Connell put their point across as television replays confirmed that the try should not have been allowed.
It left a sour taste for Declan Kidney’s men who manufactured enough attacking platforms in the closing half hour to create a match-winning seven-pointer. Sexton also missed a kickable penalty in the closing stages.
Ireland’s second defeat in the Welsh capital since 1983 ended their Championship and Triple Crown hopes, but they will have an immediate chance to put the loss behind them when title-chasing England visit the Aviva Stadium next Saturday.
The visitors suffered a setback in the opening minute. Scrum half Eoin Reddan had to be replaced after taking the full force of a Lee Byrne clearance kick in the face, Peter Stringer came on in his place.
Ireland quickly regrouped and less than two minutes later, Tommy Bowe took an outside angle, drew a tackle and passed for O’Driscoll to dive over to the left of the posts.
O’Gara continued the landmark theme by adding a conversion to bring up his 1000 points, joining the four other members of that exclusive club – Jonny Wilkinson, Dan Carter, Neil Jenkins and Diego Dominguez.
Wales did not escape during a lightning quick opening quarter, losing prop Craig Mitchell with a dislocated shoulder that meant an early introduction for John Yapp.
The home side enjoyed the lion’s share of possession and territory as the half wore on, but had only a Hook penalty to show for their efforts after his opening strike bounced back off the right hand post.
Hook then cut the gap with another penalty in the 28th minute, only for O’Gara to reply and give Ireland a 10-6 advantage.
The error count rose on a slippery pitch, but Kaplan’s willingness to allow a contest at the breakdown helped maintain a high tempo. Returning winger Leigh Halfpenny landed a superb long range penalty which kept Wales within striking distance.
But Ireland, with flanker Sean O’Brien charging into the hosts’ 22, applied the final scoring touch before the break through an O’Gara penalty after Phillips was punished for not releasing on the deck.
Sexton was sent on, ten minutes into the second half, and Ireland continued to look the more potent side. Keith Earls was as busy as ever on the left wing, and Bowe enjoyed a ding dong battle with his Ospreys colleague Shane Williams, the oldest member of the Welsh line-up at 34.
But then came Phillips’ score, which crowned his 50th cap for his country. Sexton screwed a kick straight into touch near halfway.
The ball bounced into the crowd, ruling out the quick lineout throw, but a second ball was used by Rees to send his scrum half dashing away down the touchline and in at the corner past Bowe.
Referee Kaplan consulted with Allan and swiftly blew for the try. O’Driscoll and O’Connell protested about the legitimacy of the quickly-taken lineout and the possibility of consulting television match official Geoff Warren.
But the try stood and Hook added the extras before Luke Fitzgerald had a try ruled out for a forward pass from Donncha O’Callaghan and Sexton missed a penalty he would usually convert.
With 69 minutes on the clock, Hook knocked over a sweetly-struck penalty following an offside call against O’Brien. It proved to be the final score as Ireland failed to build on some late pressure.
O’Connell knocked on in contact after a lineout in the Welsh 22 and after Sexton produced an excellent touchfinder to set up another attacking lineout, closer to the Welsh line, the visitors had one final chance.
Sean Cronin, who was sprung from the bench, connected with David Wallace towards the tail of the lineout.
Possession was recycled and moved left with great hands from Sexton and O’Driscoll, but replacement Paddy Wallace took the wrong option when cutting back inside, with Earls available outside him, and Cian Healy coughed up the ball in the dying seconds.