Estonia, who have never reached the finals of a major tournament, won their last three qualifiers to snatch second place in Group C ahead of Serbia.
Two of those victories came against Northern Ireland but their neighbours from the Republic are unlikely to be as generous. Under manager Giovanni Trapattoni, the Irish have eschewed free-flowing football for a more disciplined defensive approach.
Their pragmatic style of play won them few fans, but it was enough to secure runners-up spot behind Russia in Group B.
Whereas once the Irish could draw on a pool of players with top English sides, those days are long gone and assistant coach Marco Tardelli believes Euro 2012 represents a great chance for them to get back in the shop window.
"It's the match of their life for many players," Tardelli told reporters.
"If a player plays in the championship and maybe he plays well at the European Championships, it's possible to sign a new contract or play in the Premier League or in another country."
For the Estonians, even getting this far is something of a dream come true.
"When I was a child, I didn't have a country to dream of," former international Martin Reim said in an interview this week.
Now manager at Flora Tallinn, he won 157 caps after his country's FA was reconstituted following the fall of communism in 1991, and is the most-capped player never to appear at a World Cup.
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With Shane Long injured and Kevin Doyle suspended following his red card in the final qualifier at home to Armenia, Ireland will be looking to record international goal-scorer Robbie Keane, who has scored 51 times for his country, to lead the way.
The much-travelled Keane recently joined David Beckham when he moved to LA Galaxy from Tottenham Hotspur and netted within 21 minutes of making his debut against the San Jose Earthquakes.
The last time the Irish found themselves in a play-off it was against France as they sought to qualify for the 2010 World Cup in South Africa.
Keane netted away to France in the second leg, only to see Thierry Henry handle the ball to set William Gallas up to score and send the French to the finals.
Facing him will be an experienced Estonian defence. They may not play in Europe's top leagues, but the Estonians can boast experienced internationals like Raio Piiroja (107 caps).
On the plus side for the Irish, the Estonians failed to keep a clean sheet in any of their 10 qualifying matches, with even the Faroe Islands - managed at the time by former Ireland manager Brian Kerr - getting on the score-sheet against them.
This is the sixth time the Republic have been involved in a play-off to qualify for a major tournament and they have lost all but one of the previous five. This tie, however, marks the first time that they will play the second leg at home.
Trappatoni's men will look to get out of Tallinn with a clean sheet and an away goal at the very least to bring back to Dublin for the return leg
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