After Saturdays draw in Copenhagen, the whole country will be on the edge of their seats praying that our Boys In Green can qualify for The World Cup.
Here's all you need to know ahead of Republic of Ireland's biggest game in years.
Kick off for tonight's second leg is 7:45PM and will be live on RTE 2.
Only a win will do, 0-0 will send us to extra time and if a winner cannot be found it will be decided by spot kicks. A score draw will send Denmark to the World Cup.
Heading to the Aviva?
If you're lucky enough to be heading along to the Aviva, alongside 50,000 others you might want to get there with plenty of time to spare.
In team news:
Midfielder David Meyler is set to return for the Boys in Green after missing the first leg through suspension.
Denmark have no new injury concerns following the first leg in Copenhagen.