A win or draw at Seville's Estadio La Cartuja on Thursday, October 12, would see the Scots through to a major tournament - even a loss could do the trick if Norway fail to win in Cyprus.
It's the latest chapter in an inspirational qualifying campaign that has seen the team win five out of five games and sit atop qualifying Group A on 15 points, a run that included a memorable 2-0 win over Spain at Hampden.
But if there was any doubt of how tough a challenge they face taking on Spain in their own backyard, a glance at the match odds will provide a sobering experience.
Here are the bookies' 12 most likely results - and the odds of them happening.
9. Spain 4-1 Scotland
The odds of a punishing 4-1 triumph for Spain are 14/1. At least it would give the away fans a goal to cheer. | Getty Images
10. Spain 0-1 Scotland
The best chance of a victory for Scotland is a 1-0 win, with odds of 20/1. | Getty Images
11. Spain 5-0 Scotland
Spain are just 22/1 to win by a huge five goals without answer. | Getty Images
12. Spain 1-2 Scotland
There's odds of 25/1 on a Scottish 2-1 win against the Spanish. | Getty Images