With both sides' place in November's finals already safely booked after they had won their ties against France and the Czech Republic earlier in the week, there was, in theory, only pride to play for in Sunday's group B clash.
Yet it certainly didn't feel that way as the home side, even without their rested superstar Carlos Alcaraz and cheered on by a wildly enthusiastic full-house in the Pabellon Fuente de San Luis, defied all the odds to battle to a win that ensured they topped the group.
Matt Ebden and Max Purcell were defeated in their Davis Cup tie doubles decider. (AP PHOTO)
Jordan Thompson had served for the match in the opening rubber, only to go down 2-6 6-2 7-6 (7-3) to veteran Spanish substitute, the much lower ranked Pablo Carreno Busta, in what the Sydneysider described as an "incredibly frustrating" reverse.
But Spanish captain David Ferrer's decision to rest Alcaraz for the battle of the teams' top singles players then paved the way for Alexei Popyrin to level the tie with a fairly routine, crowd-silencing 6-4 6-4 victory over Pedro Martinez.
It set up a doubles decider, with the Aussie pair of Matt Ebden and Max Purcell, who boast an outstanding Davis Cup record, the hot favourites to prevail over the home duo of Marcel Granollers and Martinez.
With the odds stacked against them, especially with Martinez having to come back on court so soon after his defeat, things looked even more bleak for the Spaniards as they lost the opening set to the former Wimbledon champs, Ebden and Purcell.
But inspired to new levels by the din at the indoor hardcourt venue, 38-year-old Granollers, the world's No.1, helped the occasional doubles player Martinez to a remarkable 5-7 6-4 6-4 win.