Drawn in a tough-looking Group B alongside 2010 runners-up the Netherlands and dark horses Chile, the 2014 finals were always likely to provide a difficult test for both teams.
Australia, the lowest ranked side of the 32 coming into the showpiece in Brazil, were not expected to progress beyond the group stage but Spain, defending champions and winners of the past three major international tournaments, remained among the favourites to lift the famous trophy come July 13.
However, Vicente del Bosque's side were almost unrecognisable in losing their first two games, a 5-1 thrashing at the hands of the Netherlands followed up by a limp 2-0 reverse to Chile that confirmed their elimination.
While Spain will see Monday's clash in Curitiba as a chance to salvage some pride from an abysmal title defence, Australia will feel theirs remains intact after two heartening displays.
Spain's exit has caused some to suggest that their reign as the dominant force in world football is over, with speculation that Del Bosque could leave his post, but Fernando Torres believes their final fixture represents the opportunity to display their true qualities.
"We didn't show our strengths in the first two games and now we have the chance against Australia," he said.
"We're expecting a real tough game. It's our last chance to win a game at this World Cup and to go back to Spain with three points and show everyone we have a lot of football for the future."
Del Bosque could be tempted into making changes for the clash, with Koke replacing an off-colour Xabi Alonso at half-time against Chile and Diego Costa failing to impress in the loan striking role so far in the tournament.
Despite losing both matches so far - 3-1 to Chile and 3-2 to the Netherlands - Australia have impressed many with their high-intensity displays, and Tim Cahill has been particularly prominent, scoring two of his side's three goals, including a left-footed volley on the run against Louis van Gaal's side that will be a strong contender for goal of the tournament.
Unfortunately for head coach Ange Postecoglou, Cahill will miss the final game through suspension having picked up a booking in each of the previous matches.
Experienced campaigner Mark Bresciano is likely to miss out with a hip problem, while Mark Milligan (hamstring) is also a doubt.
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