Seamus Coleman's Republic of Ireland sealed a World Cup qualification play-off berth by beating Wales 1-0 in an edgy encounter at Cardiff City Stadium.
Ireland's victory, earned when West Bromwich's James McClean converted Jeff Hendrick's 57th-minute cross, means Ashley Williams's Wales's hopes of being in Russia next summer are over.
Everton centre-back Williams captained Chris Coleman's team in what was their first defeat of a 10-match qualifying group. Indeed, the Welsh conceded only seven goals during the campaign but ultimately paid the heaviest of prices for drawing half of their matches.
Ireland's triumph saw them finish two points behind Group D winners Serbia and Martin O'Neill's side, who were watched by Everton full-back and Ireland skipper Coleman in the Welsh capital, go into the 17 October play-off draw.
The eight best second-placed teams in European qualifying will be pitted into four two-legged ties, with the victors joining the nine group winners in next year's finals.
Gylfi Sigurdsson is guaranteed his place at the tournament after Iceland added another chapter to their remarkable latter-day story by becoming the smallest nation to reach a World Cup.
Toffees' record signing Sigurdsson set his team on the way to the victory over Kosovo they knew would book their passage to Russia with a sweetly-taken goal five minutes before half-time.
The 28-year-old then turned provider, setting up Burnley's Johann Berg Gudmundsson for Iceland's second and final strike on 68 minutes.
Iceland, with a population of fewer than 350,000, will assume Trinidad & Tobago's mantle as the smallest country to have played on intenational football's biggest stage – two years after they stunned England in a European Championship last-16 encounter.
Everton Under-23 midfielder Harry Charsley was on target for Republic of Ireland Under-21s in their 4-0 win over Israel in Dublin.
Reece Grego-Cox of QPR bagged a hat-trick as the Irish made it a fourth game unbeaten to sit top of European Championship 2019 qualifying Group 5.
And Nikola Vlasic was the third Everton player in the goals today. Attacker Vlasic hit a double as Croatia Under-21s routed visitors Czech Republic 5-1 to remain at the Group 1 summit and on course for the finals in Italy and San Marino in two years' time.