Wales' 2018 World Cup hopes are over after James McClean's goal earned the Republic of Ireland a victory that sends them into the qualifying play-offs.
At a highly charged Cardiff City Stadium, the hosts controlled much of the first half but were frustrated by the stout defending and rugged physicality of their opponents.
The Republic grew in confidence after the interval and their abrasive approach paid off as Jeff Hendrick dispossessed Wales captain Ashley Williams and set up McClean to score with a thumping half-volley.
Wales hurled bodies forward in a desperate late search for the two goals they needed to snatch the play-off place back from Martin O'Neill's side, but they found their route to goal blocked by an unflinching Irish defence.
Although the game lacked quality on occasions, the high stakes made for an absorbing encounter.
Only victory would have guaranteed either team a place in the play-offs, while a win coupled with a Serbia defeat - or draw in Wales' case - would have seen them qualify automatically.
However, Serbia's home victory over Georgia rendered that scenario academic and secured their passage to next year's tournament in Russia as Group D winners.