James McClean fired Republic of Ireland into the World Cup qualifying play-offs and dumped Wales out in the process with a 1-0 win in Cardiff.
In a winner-takes-all clash for the runners-up spot in Group D behind Serbia, McClean hammered home just after half-time as Ireland put on a defensive masterclass to deny the 2016 European Championship semi-finalists, who had not lost at home in four years.
The result means Gareth Bale, who was missing through injury, and his team-mates will spend a summer at home while Ireland can look forward to a two-legged play-off for a place in Russia.
Martin O'Neill's side find out their opponents next Tuesday.
In a cup final atmosphere, the game rarely sparked into life with both sets of players keen to stay in their respective shapes.
Hal Robson-Kanu headed over a presentable chance from a Joe Ledley corner early on, but they rarely tested a disciplined back four shielded by skipper David Meyler.
Player ratings
Wales: Hennessey (5), Gunter (6), Davies (6), A Williams (5), Chester (6), Allen (6), Ledley (6), Ramsey (6), King (6), Lawrence (6), Robson-Kanu (6)
Subs: Vokes (6), Williams (6), Woodburn (6)
Away Team: Randolph (7), Christie (6), Clark (8), Arter (6), Duffy (8), Hendrick (8), McClean (8), Ward (7), Meyler (8), Brady (7), Murphy (6)
Subs: Long (6), Whelan (6)
Man of the match: James McClean
The hosts suffered a blow 10 minutes before the break when Allen was caught in a sandwich of Meyler and McClean and forced to leave the field.
Darren Randolph tipped over Robson-Kanu's diving header just after the break before the key moment of the game came on 57 minutes.
Team news
Chris Coleman went for pace rather than power up front by handing a start to Hal Robson-Kanu over Sam Vokes in the only change from their win over Georgia. There were three changes made by Martin O’Neill. Robbie Brady and James McClean returned from suspension while Harry Arter was preferred to Wes Hoolahan. Daryl Murphy started up front in Shane Long’s absence.
Wales skipper Ashley Williams lost possession on the edge of his penalty area and Jeff Hendrick crossed for McClean to slam home his fourth goal of the campaign.
There was plenty of time for Wales to stage a rally, but Ireland, who had less than 30 per cent possession, soaked up all the pressure and were in no mood for budging.
Man of the match - James McClean
The West Brom winger has been the go-to-guy for the Republic in this qualification period - and once again - when it mattered - he stepped up. Most players would have snatched at his only opportunity of the match, especially with their weaker foot, but McClean skilfully pinged his effort right where Hennessey couldn't reach it. Special mention has to go to the axis of Shane Duffy, Ciaran Clark and Meyler who were all outstanding in repelling Wales' threat.
Manager reaction
Martin O Neill
"I'm so proud. The players were magnificent playing away from home at a very good Welsh side. To win on their territory was a great result for us."
Chris Coleman
"Right now all I can think about, picture in my mind, is the faces of the players in the dressing room and the disappointment. They are inconsolable at the moment but they should feel very proud. That's all I can think about."