England's chariot will roll into Dublin this week in search of back-to-back titles, and the only joy Ireland can derive from the whole thing will be from stopping them breaking a world record and winning another Grand Slam.
On the evidence of last night's efforts, Eddie Jones better pack some champagne in his suitcase.
The title is gone for another year as a result of this dispiriting, try-less performance under the Millennium Stadium roof. After their brilliant autumn, Joe Schmidt's side wilted in the white heat of Championship action.
There were echoes of Murrayfield as the coach seemed put out by conditions beyond his control, complaining about the moisture on the pitch even before a ball had been kicked.
Losing Conor Murray was a blow, but Schmidt persisted with the clearly injured scrum-half for too long and when he finally introduced Kieran Marmion - who played well - his side were chasing the game from nine points down.
They still had a succession of chances to win it after Johnny Sexton had narrowed the gap to six but their attacking execution was well below the standard needed, and if they had played on for a few more hours the red wall wouldn't have breached.
It was a proud performance from a Welsh side wounded from two weeks of relentless criticism. They were well worth their win, with George North in particular giving a resounding answer to the doubters, and a number of players doing their Lions chances no harm at all.
Ireland looked pumped up in the build-up and the opening exchanges suggested they had learned from their slow starts. O'Brien almost picked off Rhys Webb, Jack McGrath dispossessed Alun-Wyn Jones and Sexton sent Simon Zebo down the left wing with a cut-out pass to put Wales on the back foot from the off.
After a frantic start, Sexton settled things down and opened the scoring with a tough penalty after Webb went high on Robbie Henshaw.
Ireland were deploying Italy's no-ruck tactic, but it back-fired when O'Brien failed to spot CJ Stander engaged in a ruck and gave away the penalty.
Now, it was Ireland's turn to defend through a lengthy set of phases with the Tullow flanker and Henshaw putting in shuddering hits as the rearguard remained patient, and ultimately the error came.
It was frantic stuff; Dan Biggar rescued his side by beating Garry Ringrose to Zebo's kick through.
From the drop-out, Sexton sent the ball skyward and when Leigh Halfpenny failed to gather Stander went into Jonah Lomu mode, busting two tackles until he was hauled down by Ross Moriarty. Ireland failed to take the penalty advantage and kicked the ball into touch. But Alun-Wyn Jones got up in the five-metre lineout to beat Jamie Heaslip to the ball and the chance passed.
Ireland suffered a blow when Sexton headed off for a Head Injury Assessment after his head collided with Jonathan Davies' knee.
After a long delay, Wales took their chance with a brilliant set-piece try. From clean off-the-top ball, Webb worked a neat one-two with Scott Williams to by-pass Paddy Jackson and delivered a sensational long pass for the on-rushing Halfpenny. He drew a defender and released North, who rolled back the years by barrelling through Keith Earls and Zebo to score.
Halfpenny missed the conversion and Rob Kearney caught the restart to take the fight back to the home side. Ireland turned to their maul and began to exert major pressure, forcing three penalties before opting for Jackson to kick his team back into the lead, and with that he was whisked off for Sexton's return.
The game settled into a lull as Murray twice stayed down after tackling North but continued as Ireland were forced to spend long periods without the ball and in their own half.
A Tadhg Furlong knock-on invited Wales to attack again and when Webb was handed advantage he kicked wide for Liam Williams, who off-loaded to Halfpenny who in turn found Davies. Sexton nailed him on the line, but was penalised for killing the ball and as Halfpenny put his side back in front, the Ireland No 10 headed for the sin-bin.
Despite clearly struggling with his wrist injury, Murray continued beyond half-time as Zebo slotted in to out-half. Ireland started the second half with plenty of possession, but didn't look like they knew what to do with it and when O'Brien's pass went to deck Webb kicked in behind and forced Murray into touch.
They cleverly mauled the ball in-field, before working the ball back for Webb to feed North, who scored his second in the corner.
Halfpenny nailed the touchline conversion to make it a nine-point game and Ireland then had to survive 17 phases of Welsh pressure in their own '22' before Marmion, just on for Murray, bundled Moriarty into touch.
Sexton returned, and with Marmion's pass speeding up their game and Garry Ringrose growing into things, they went through 26 phases before forcing a penalty.
Rory Best ordered the ball be kicked to touch and while the maul didn't go anywhere, a harsh high-tackle call on Biggar allowed Sexton close the gap from under the posts to make it 15-9
A poor Henshaw kick invited Wales to attack once again but Biggar's attempted drop-goal struck the post and a Justin Tipuric push allowed the visitors to clear.
Two Irish lineouts went a-begging just as they needed to exert some pressure but Iain Henderson stole the ball back and Sexton pinned the Welsh back on their own line to begin a mad few moments as an Henderson got a hand on a Biggar clearancxe, but Furlong knocked on when it fell into his lap.
Ireland had to settle for a lineout on the edge of the '22' and this time the ball stuck and while attempts to set up a maul came to nothing, Henshaw's dab in behind forced Halfpenny into touch.
This seemed like the chance, a five-metre lineout, and while the throw was successful, Henshaw got himself in an offside position at the maul and another chance passed.
They then kicked two consecutive cross-kicks in an attempt to break the red wall but the second evaded Earls.
From the Welsh lineout, Donnacha Ryan and Marmion got pressure on Gareth Davies and forced a five-metre scrum.
But again, Ireland couldn't execute and over-elaborated as Earls knocked on and Henshaw played the ball off-side to allow Biggar to clear.
Instead of attacking from a position of strength, Ireland were being forced to chance their arm and they were punished by Jamie Roberts, who pounced after Sexton's kick was charged down to settle the result.
Three tries to nil brooked no argument. Ireland's season of promise has gone horribly wrong.
WALES - L Halfpenny; G North, J Davies, S Williams (J Roberts 67), L Williams; D Biggar, R Webb (G Davies 67); R Evans, (N Smith ), K Owens (S Baldwin 72), T Francis (S Lee 70); J Ball (L Charteris 63), AW Jones (capt); S Warburton, J Tipuric, R Moriarty (T Faletau 67).
IRELAND - R Kearney (T Bowe 79), K Earls, G Ringrose, R Henshaw, S Zebo; J Sexton (P Jackson 19-27 HIA, 79), C Murray; J McGrath (C Healy 59), R Best (N Scannell 79), T Furlong (J Ryan); D Ryan, D Toner (I Henderson 63); CJ Stander (P O'Mahony 63), S O'Brien, J Heaslip.
Ref - W Barnes (England)