Wales and the Republic of Ireland both head towards history tonight in their crucial meeting at the Cardiff City Stadium.
The home side have only ever reached one World Cup final in their history, in Sweden in 1958, and they know that avoiding defeat tonight will see them earn a play-off spot with a chance of making Russia next year.
For Ireland meanwhile, they're looking to make their first appearance at the event since South Korea and Japan in 2002, where they lost to Spain on penalties in the round of 16.
Both sides can still top the group thanks to Serbia's 3-2 defeat to Austria on Friday. Ireland need to win and hope Serbia lose to Georgia, a somewhat unlikely result, and Wales have to hope they win and hope Georgia take at least a point.
And with home advantage, Wales are looking to their national anthem to give the players an early boost ahead of the game.
The Wales team have requested that the music on the anthem be cut after the first few bars, and that the fans take over from there.
Hen Wlad Fy Nhadau is one of the most passionate anthems around, with supporters singing an a cappella version during their Euro 2016 qualifier against Belgium two years ago.
The power of the song that night inspired Wales to record a historic 1-0 win on their road to qualifying for the tournament, where they famously reached the semi-final stage.
It has been heard at significant points of games since that night, notably during Wales' crucial win against Austria last month, when Ben Woodburn struck a stunning winner from distance.
Chris Coleman’s team have no formulated the plan to inspire themselves and the crowd with the way the anthem will be sung, having taken inspiration from a fault before their 1-0 win in Georgia on Friday.
The Georgian FA cut the music by mistake after the first verse, then tried to start the hosts' own anthem.
But they were denied by the 2,000 travelling fans, who continued to finish the chorus, while the players remained arm-in-arm to end it with them.
It is set to be a night to remember in the Welsh capital, with Ireland taking 3,000 of their own supporters to make a memorable occasion.
Both teams are aiming to make their second successive major tournament, and Coleman has urged Wales fans to be in their seats before his side go out to warm-up in Cardiff.