Republic of Ireland's hopes of reaching next summer's European Championships were cruelly ended on penalties as Slovakia progressed to the play-off final after a 0-0 draw in Bratislava.
Alan Browne had golden chances to win it for the visitors in open play, but the Preston midfielder and Matt Doherty missed the crucial penalties as the hosts prevailed 4-2 in the shootout.
It means Slovakia will progress to face Northern Ireland for a place in next summer's tournament after they beat Bosnia & Herzegovina on penalties during a dramatic night of European Qualifying play-offs.
Republic of Ireland will have to lick their wounds and renew their Nations League campaign this Sunday when they face Wales, but this is a defeat that may well linger for some time.
Slovakia: Rodak (8), Pekarik (7), Vavro (7), Valjent (7), Mazan (6), Kucka (6), Hrosovsky (6), Hamsik (7), Rusnak, Duda (6), Mihalik (6).
Subs: Haraslin (7), Gregus (7), Bozenik (6), Mak (6).
Republic of Ireland: Randolph (7), Doherty (7), Duffy (7), Egan (7), Stevens (7), Hendrick (6), McCarthy (6), Hourihane (6), Robinson (6), McGoldrick (7), McClean (6).
Subs: Brady (7), Long (6), O'Dowda (7), Browne (7).
Man of the match: Marek Rodak.
Shootout despair for Boys in Green
Goals have been a problem for this Republic of Ireland side, who had scored just 14 times in their previous 16 games ahead of the game in Bratislava. Indeed, no Republic of Ireland player had scored more than once in Euro 2020 qualifying so far with their seven goals all scored by different players.
But Stephen Kenny, still searching for his first win as Republic of Ireland manager in only his third competitive match, would have been encouraged by the opening 45 minutes as his side restricted the industry of Marek Hamsik and carved out a few chances of their own.
Republic of Ireland boss Stephen Kenny turned to experience. David McGoldrick and James McClean were drafted in alongside Callum Robinson in attack as Kenny teamed up James McCarthy, Conor Hourihane and Jeff Hendrick in midfield for a must-win game in Bratislava.
Opposite number Pavel Hapal was able to include returning skipper Marek Hamsik in his starting line-up at the Narodny Stadium, but was without Milan Skriniar and Stanislav Lobotka because of coronavirus restrictions and David Hancko through injury.
The best fell to James McClean after 37 minutes but after Conor Hourihane laid off Doherty's deep cross, the Stoke winger's goalbound shot was well blocked by Martin Valjent.
Slovakia didn't threaten until first-half stoppage time when Darren Randolph saved well low down from Ondrej Duda, and from the ensuing corner, the Cologne midfielder's overhead kick flashed a yard wide of the post.
Browne was introduced in the second period, and he made an instant impact as he collected David McGoldrick's pass and forced Marek Rodak into a smart save at his near post.
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Slovakia manager Pavel Hapal looked for a similar impact off the bench and Lukas Haraslin very nearly had the desired effect as the substitute took Hamsik's pass, cut inside Doherty but his shot was brilliantly cleared off the line by Shane Duffy.
With the contest heading for extra time, the visitors ought to have won it when McGoldrick sent Callum Robinson clear of the last defender. Having unselfishly teed up Robbie Brady for the cross, Hourihane was unable to direct the ball over the line from close range as his shot was blocked by Juraj Kucka.
With the stalemate still not broken, the game hurtled into an additional 30 minutes, but again Republic of Ireland came within inches of the breakthrough as Browne was then denied by a goal-line clearance after good work from Doherty to keep alive Hourihane's corner.
Further agony was to come on the stroke of the interval in extra time as Brady and Callum O'Dowda combined down the left before Browne's near-post shot cannoned off the foot of the post.
It didn't look like being Browne's night, and so it transpired in the inevitable shootout. Hamsik made no mistake before Hourihane levelled it up. Patrik Hrosovsky and Brady both found the net before Haraslin kept Slovakia in front.
But then up stepped Browne, and Fulham stopper Rodak guessed correctly to his right. Jan Gregus turned the screw with a Panenka finish to heap the pressure on Doherty. Rodak wasn't required again as the full-back fired onto the crossbar to end his country's dreams of playing at the tournament they will help host next summer.
Kenny: It's a cruel way to lose
Republic of Ireland boss Stephen Kenny: "I couldn't have asked for more from my players. They showed great qualities as men and as Irishmen. They showed themselves to be a real team, and everyone did as much as they could tonight. As the game progressed, I felt we were in the ascendancy and looked like we really wanted to win it.
"We had some good chances but just couldn't find the goal we needed. Right at the end of the game and in extra-time we had chances and it's a very harsh way to lose but it's the way it goes.
"I don't think you could say it's bad luck but the players did everything they could to win the game. The work rate was phenomenal. They didn't deserve to lose the game, and the determination to try and win tonight to get to the play-off final was very evident.
"It's a cruel way to lose on penalties. We defended well all night and created some good chances. Some of the forward play, especially from David McGoldrick, was outstanding at times. The players deserved better."
Connolly, Idah forced into late withdrawal
Kenny confirmed afterwards that Aaron Connolly and Adam Idah were dramatically ruled out at the last minute after it emerged that a second FAI staff member had tested positive for Covid-19.
The Republic of Ireland boss added: "We have different rules in Ireland compared to the UK. They're much more stringent over what's deemed close contact with one of our members of staff. It's very harsh for them to be ruled out as they're perfectly fine and there's nothing wrong with them but we have to abide by the medical advice.
"We did know a little earlier and there was an appeal on the basis of how far they were away from each other but it wasn't deemed sufficient so there's nothing we could about it. We don't have any issues in the camp at all, it was just with a non-footballing member of staff. This is just one of the rules we have to adhere to."
Analysis: World Cup must be the next goal
Former Republic of Ireland defender Phil Babb told Sky Sports:
"I'm gutted and it's such a cruel way to go out. The two lads that missed in the penalty shootout didn't deserve that as we were by far the better team. We weathered the storm and then handled everything Slovakia could throw at us. We grew into the game and had we been more clinical on another day, we could've won the game 2-0 or 3-0.
"It's a bitter pill to swallow because of the possession and the chances they created. We've seen the development of the side tonight after the two Nations League games. This was a polished, well-drilled performance. It will be a very quiet dressing room and it will be very hard for them to pick themselves up. The Nations League is now a chance to get to the World Cup play-offs and that has to be the next goal."
'It's hard to put into words'
Republic of Ireland defender Shane Duffy told Sky Sports: "We're disappointed and it's hard to really put it into words. It's never nice to lose on penalties so it's a tough one to take at the minute. We created chances and it just wasn't our night when things just didn't drop for us.
"Both teams cancelled each other out in the end and penalties is the luck of the draw. It's hard to take. They had four good penalties to be fair and our lads were brave stepping up to take one. We'll get back together and go again."
Man of the match - Marek Rodak
Slovakia were without their No 1 but Rodak rose to the occasion to send his country to within 90 minutes of their second successive European Championships.
Newcastle goalkeeper Martin Dubravka remains out with an injury, but the Fulham stopper won his duel with Browne, first preserving his clean sheet before guessing right to hand the hosts the initiative in the shootout.
Having been one of the better goalkeepers in the Championship last season, Scott Parker may well wonder if he needed to bring Alphonse Areola to the club during the summer.
Lack of clinical edge costs Irish - Opta stats
- The Republic of Ireland are without a win in seven competitive games (D5 L2), only enduring a longer run in 1972 (14 games).
- Slovakia secured just their third clean sheet in their last 18 matches in all competitions.
- The Irish have failed to score in four of their last six competitive games (2 goals scored in total), after netting in five in a row before that.
- The Republic of Ireland have been knocked out in each of their last two single-leg play-off matches for the European Championships, also losing back in 1995 against the Netherlands.
Live UEFA Nations League
UEFA Nations League
The winners of each of Thursday's semi-final ties in the pathways face each other in the European Qualifying play-off finals on November 12 for a spot at Euro 2020. The winner of Northern Ireland vs Slovakia will join Poland, Sweden and Spain in Group E at Euro 2020.
- Path A: Hungary vs Iceland
- Path B: Northern Ireland vs Slovakia
- Path C: Serbia vs Scotland
- Path D: Georgia vs North Macedonia
Republic of Ireland resume their Nations League campaign against Wales at the Aviva Stadium at 2pm on Sunday, live on Sky Sports. The Irish then travel to face Finland on Wednesday at 5pm, also on Sky Sports.
Slovakia face Scotland in the Nations League on Sunday at Hampden, live on Sky Sports; kick-off 7.45pm.