Wales ended Ireland's 10-match winning streak and Grand Slam hopes with a 23-16 victory in Cardiff on Saturday.
The result means that three teams – Ireland, England and Wales – are in contention to lift the Six Nations trophy next weekend.
The hosts twice led by relatively comfortable margins only for the Irish to fight their way back into the game.
Paul O'Connell's men pushed hard for a converted try in the dying stages of the match, which would have secured a draw, and felt they should have been awarded another penalty try when their driving maul collapsed. Referee Wayne Barnes didn't agree, however, and Wales were able to hang on for the win.
The Dragons had led 12-0 after 14 minutes thanks to four penalties from Leigh Halfpenny, before Johnny Sexton got Ireland on the board with a penalty.
A good passage of play for the visitors saw them earn another penalty, this time close to the right-hand touchline. They kicked for touch but lost the lineout, with Sam Warburton making the steal at the back.
Warburton was then yellow-carded in the 28th minute after yet another infringement from the Welsh at the breakdown and Sexton kicked the penalty.
Wales, though, were able to add to their tally while down to 14 men, through a Dan Biggar drop goal, which was followed by Sexton's third penalty that made it 15-9 at half-time.
The hosts then struck a crucial blow in the 62nd minute when, after a 15-phase attack, replacement Scott Williams dived over the tryline.
Ireland stormed back into Wales' red zone and should have scored with a three-man overlap out wide, but Cian Healy went for the line and lost possession.
The visitors did get themselves back into the game when they were awarded a 68th-minute penalty try after Wales collapsed a driving maul.
The Irish conceded another three points when they were penalised for holding on, but found themselves up against 14 men again, when Jonathan Davies was sin-binned for an intentional knock-down with two minutes to go.
They kicked for the corner only to lose the 5m lineout, and while they won the next lineout, Wales were able to hold up the driving maul, much to the disgust of O'Connell, whose 100th Test for Ireland ended in defeat.
Wales – Try: Scott Williams. Penalties: Leigh Halfpenny (5). Drop goal: Dan Biggar.
Ireland – Try: Penalty try. Conversion: Johnny Sexton. Penalties: Sexton (3).
Wales – 15 Leigh Halfpenny, 14 George North, 13 Jonathan Davies, 12 Jamie Roberts, 11 Liam Williams, 10 Dan Biggar, 9 Rhys Webb, 8 Toby Faletau, 7 Sam Warburton (c), 6 Dan Lydiate, 5 Alun-Wyn Jones, 4 Luke Charteris, 3 Samson Lee, 2 Scott Baldwin, 1 Gethin Jenkins.
Subs: 16 Richard Hibbard, 17 Rob Evans, 18 Aaron Jarvis, 19 Jake Ball, 20 Justin Tipuric, 21 Mike Phillips, 22 Rhys Priestland, 23 Scott Williams.
Ireland – 15 Rob Kearney, 14 Tommy Bowe, 13 Jared Payne, 12 Robbie Henshaw, 11 Simon Zebo, 10 Johnny Sexton, 9 Conor Murray, 8 Jamie Heaslip, 7 Sean O'Brien, 6 Peter O'Mahony, 5 Paul O'Connell (c), 4 Devin Toner, 3 Mike Ross, 2 Rory Best, 1 Jack McGrath.
Subs: 16 Sean Cronin, 17 Cian Healy, 18 Martin Moore, 19 Iain Henderson, 20 Jordi Murphy 21 Eoin Reddan, 22 Ian Madigan, 23 Felix Jones.
Photo: Dan Mullan/Getty Images