Great Britain will compete in the Sydney city final of the inaugural United Cup after a 4-1 victory over Spain in their final Group D series.
Tim Henman's team entered New Year's Day with a 2-0 lead over the Spaniards, but that was reduced immediately as Paula Badosa came from a set down to beat Harriet Dart 6-7 7-6 6-1 in a three-hour thriller.
However, Dan Evans's 6-3 1-6 6-3 win over Albert Ramos-Vinolas gave GB an unassailable 3-0 lead heading into the final doubles rubber, where Dart and Jonny O'Mara overcame Jessica Bouzas Maneiro and David Vega Hernandez 3-6 6-2 10-5.
Kicking off January with a bang, Badosa and Dart fought fiercely for over three hours in the day's opening contest, but the Briton just could not keep pace with the world number 13 in the third set after two hotly-contested tie-breakers.
A double break for Dart brought up a 5-2 lead in the first set, but Badosa responded by winning four games on the bounce before the Briton took her second set point in the tie-breaker.
Both players earned three breaks - including a remarkable four in a row between games nine and 12 - in the second set, where Badosa would seemingly fail to build on a 5-0 lead in the tie-breaker as Dart reduced the deficit to 5-4.
The Spaniard eventually came through to force a third set, where Dart's exhaustion began to take its toll, as she held in her opening service game before losing the next five in a row to succumb to defeat.
Evans was due to take on Pablo Carreno Busta in the following singles match, but the latter had to be replaced by Ramos-Vinolas due to injury, and Evans took two hours and 19 minutes to post a three-set win and confirm GB's place in the city final.
A late change in opponent initially made no difference to Evans, who raced into a 3-0 lead in the opening set and held convincingly to convert his third set point.
However, a few more errors on the Evans forehand opened the door for Ramos-Vinolas in the second set, as the Spaniard strung together a five-game winning streak before levelling the match with an ace.
Refusing to let his second-set slip get the better of him, Evans roared back in the third, breaking the world number 39 twice more and sending GB through to the finals with a fifth ace of the day - four of which came in the third set.
Evans was due to join forces with Dart to face Badosa and Rafael Nadal in the doubles match, but O'Mara was drafted in as Spain instead called upon Bouzas Maneiro and Vega Hernandez, who could not restore parity as they lost to the Sydney finalists in one hour and 12 minutes.
A few double faults bedevilled Dart and O'Mara in the first set as Spain gleaned an early advantage, but the British pair recovered well in the second set - earning four breaks, albeit while being broken twice themselves.
A love hold levelled the contest for GB ahead of the first-to-10 tie-breaker, where a number of Spain shots into the net brought up four match points for Dart and O'Mara, who needed just the one as Bouzas Maneiro returned wide.
Great Britain have three days to recover before meeting the winner of Group C - either Germany, the USA or the Czech Republic - in the Sydney city final on January 4 for the chance to make the overall semi-finals.