James McClean blasted the Republic of Ireland into the play-offs with a decisive goal in the winner takes all World Cup European Qualifying Group D clash at the Cardiff City Stadium as Martin O'Neill's side emerged 1-0 winners.
Wales were firm favourites to get the result they needed to pip Ireland, but a dogged and determined display by the men in green secured a famous win.
The road to Russia continues for Ireland thanks to McClean's winner, his fourth of the campaign, it was also a master class of defending, being patient, waiting for that one crucial chance and when they got it, there was no way back for the home side.
It had all started so well for Wales, with only four minutes gone they looked threatening with Ledley whipping in a near-post cross which Robson-Kanu headed over the bar.
In the next raid it was Aaron Ramsey who went for goal from about 25 yards out but Darren Randolph got a slight touch to keep it out.
Ireland were struggling to get out of their own half as Wales pressed forward seeking an early breakthough.
It took just over 30 minutes before Ireland got a sight of a goal, Wales failed to clear their lines and when the ball eventually fell to Shane Duffy his angled shoot just went the wrong side of the far post.
Wales dominated the first half as far as possession but Ireland did manage to create a couple of good chances and towards the break were beginning to edge further away from their own penalty box.
In added time Robbie Brady almost found a way through when he drifted from the right wing into a shooting position but his ambitious shot from a tight angle went straight to keeper Wayen Hennessy.
The second half was only a few minutes old when Wales again threatened, this time Ramsey flicking a header into the side netting.
It took a stunning save by Randolp to keep it level. Ashley Williams curled in a brilliant cross, Robson-Kanu connected with a powerful header but Randolph leapt up to flick it over the bar.
How crucial that save proved to be - Wales could easily have been ahead - but within four minutes Ireland stunned the home fans by taking the lead.
Jeff Hendrick pounced on a lapse by Williams and surged down the wing before delivering a cross for the lurking James McClean who was on hand to smash the ball home with a first-time shot and Ireland, who had soaked up so much pressure had turned the game on its head.
Conceding the goal was bad enough for Wales, but with Croatia taking the lead against Ukraine it meant they needed to win to get into the play-offs.
Wales tried to find a way back, but Ireland were solid and resolute and at the end of what has been an absorbing campaign, O'Neill's side finished second on 19 points and now all eyes will be on the draw next Tuesday.