The Australian team of Stosur and Tomic will finish last in Group A behind Italy's Flavia Pennetta and Andreas Seppi, Canada's Eugenie Bouchard and Milos Raonic, and the finalists from Poland Radwanska and Panfil having lost all three ties.
Australia's Hopman Cup campaign started disastrously when both Tomic and Stosur lost their singles matches against Canada on Saturday night with Tomic's non-competitive second set performance against Raonic particularly disappointing.
However, the Australian pair won the mixed doubles to keep hopes of reaching the final still alive heading into Tuesday's clash with Italy.
Stosur again lost to Pennetta 6-4, 6-4 before Tomic found some form after dropping the first set to beat Seppi 4-6, 6-3, 6-2.
Australia lost the mixed doubles, though, to end their Hopman Cup dreams for yet another year.
Poland, though, despite being the No. 1 seeds have been the great surprise packets of the week and now could very well be one of the most unlikely finalists in the tournament's history.
The Polish team was handed the No. 1 seeding when world No. 5 Radwanska was to be partnered by rising star Jerzy Janowicz, but he withdrew due to injury and when he was replaced by the 288th-ranked Panfil it appeared Poland's hopes at the Perth Arena went out the door with it.
Poland started brightly on Saturday beating Italy 3-0 even though the victory was gifted to them due to an ill Seppi for the Italians.
The Poles then moved into the box seat to make the final with a terrific win on Sunday night over Canada when Radwanska beat Bouchard 6-3, 6-7, 6-2 and then Panfil record the upset of the week and the win of his career beating world No. 11 Raonic 7-6, 6-3.
However, Canada won the mixed doubles on that night and then when the Canadians were gifted victory over Italy on Thursday due to a wrist injury to Pennetta, suddenly the race was on to be the finalist from Group A between Canada and Poland.
Poland headed into the Thursday night clash with Australia needing to win to ensure of a place in the final, but the home team was desperate to finish their Hopman Cup campaign on a positive note.
Things started well for Australia when Tomic recorded his second singles win of the week comfortably beating Panfil 6-1, 6-4 to open the tie.
The pressure was then on Stosur to find some form and head to Hobart with some momentum coming off disappointing losses to Bouchard and Pennetta, but the world No. 5 was not going to give it to her easy.
Once again, Stosur started well and took the first set, but she couldn’t keep it going with her unforced errors continually letting her down as Radwanska took care of the last two sets to win 3-6, 6-4, 6-3.
That set up a mixed doubles clash where Poland had to at least claim a set to qualify for the final or to leave the door open for the Canadians.
Stosur and Tomic looked set to finish Australia's Hopman Cup off on a positive note winning the first set 6-1, but the Polish team then rebounded to claim the second 7-5 and then won the deciding Match Tie-Break 10 points to eight too book a place in the final.
Poland will now prepare for Saturday's final but will not know who their opponent will be potentially until late Friday night.
Heading into the final day of the round-robin format, the USA's Sloane Stephens and John Isner, Czech Republic's Petra Kvitova and Radek Stepanek, and France's Alize Cornet and Jo-Wilfried Tsonga all remain in contention to make the final.
Only the makeshift Spanish team of Anabel Medina Garrigues and Daniel Munoz-De La Nava are out of the running.
France simply has to beat Spain in the day session to book in a final berth but a loss for Cornet and Tsonga, will mean that whoever wins on Friday night between the USA and the Czech Republic could book in a meeting with Poland on Saturday.