England a win away from Six Nations glory as Wales beat Ireland
George North scored two tries as fired-up Wales floored Ireland in Cardiff - and left England one win away from retaining the RBS 6 Nations title.
England will secure Six Nations silverware for a second successive season if they beat Scotland at Twickenham on Saturday after North blew away their closest challengers.
Ireland needed victory to set up a potential title decider against England in Dublin next week, but Wales had other ideas as they triumphed 22-9 and claim a biggest sin against Ireland since 1983.
Full-back Leigh Halfpenny added a penalty and two conversions, while substitute centre Jamie Roberts touched down two minutes from time as Ireland played almost a quarter of the match without their fly-half talisman Johnny Sexton, who went off for a head injury assessment and was later sin-binned.
Sexton booted two penalties and Paddy Jackson one, but Wales profited from Sexton's yellow card, scoring 10 points while he was temporarily sidelined, and it left Ireland with too much to do.
England now know that victory over the Scots would equal New Zealand's world record of 18 successive Test wins and see them crowned Six Nations champions once more.
Wales boss Rob Howley was criticised for retaining the entire team and replacements' bench following defeat against Scotland two weeks ago, but his players responded magnificently as they staved off what would have been a 10-year low of three successive Six Nations losses in one season.
Ireland made a strong start, not only going in front through Sexton's sixth-minute penalty, but forcing Wales back through through the sheer ferocity of their attacking game.
Sexton opened the scoring after Wales scrum-half was punished for a high tackle on Ireland centre Robbie Henshaw, and Wales continued to not help themselves as fly-half Dan Biggar saw a pass intercepted by Keith Earls and the visitors again motored up field.
But Wales began to give as they got during a thunderous opening punctuated by some bone-crunching tackles, notably Henshaw's hit on Wales prop Rob Evans, before Sexton departed for a head injury assessment after Wales centre Jonathan Davies' knee accidentally caught him in the face.
Sexton's left eye showed signs of swelling before he had even left the pitch, and his replacement Paddy Jackson barely had time to settle before Wales conjured a magnificent 20th-minute try.
Livewire Webb broke clear in midfield following a lineout, then linked with centre Scott Williams before firing out a long pass to Halfpenny, who sent North powering over for his 29th Wales touchdown in 68 Tests.
It was comfortably Wales' best try of the tournament, and although Halfpenny sent the touchline conversion attempt wide, the home side led 5-3 after a pulsating opening quarter.
Jackson then kicked Ireland in front just before Sexon returned following a nine-minute absence, but Wales finished the first-half on top and Halfpenny kiched them ahead as Sexton's eventful night continued.
On this occasion he was yellow-carded by referee Wayne Barnes for killing possession on Ireland's line following a tackle on centre Jonathan Davies, who almost scored when Webb's clever kick found Liam Williams, before Halfpenny's pass sent Davies to within touching distance.
Sexton looked perplexed at the decision, and Halfpenny's simple penalty made it 8-6, ending a gripping 40 minutes that enthralled a capacity 74,000 crowd.
And Wales were in no mood to ease up, as they increased their lead just four minutes into the second period.
After gaining a lineout deep inside Ireland's 22, the forwards drove relentlessly before Webb had a simple task of sending an unmarked North over for his 30th Wales try.
Halfpenny added the conversion, and Ireland had it all to do, trailing 15-6 and their Six Nations title hopes slowly but surely beginning to ebb away.
Sexton cut the gap with his second penalty, and that was the cue for Ireland to put together a sustained spell of pressure which tested Wales' defence s both coaches began to make substitutions at regular intervals.
But Ireland blew a golden opportunity when Henshaw was penalised just inches from Wales' line, and the home side prevailed, despite the visitors again laying siege during a frantic finale, as Roberts marked his 90th cap by finishing them off.