If Harriet Dart loses to Ajla Tomljanovic in the next singles rubber, Australia will secure victory.

If the Briton wins, the best-of-three tie will go to a deciding doubles.

Britain have been the underdogs throughout the competition and face another uphill task to reach the final after Watson's defeat.

But one thing we have learned about Anne Keothavong's side this week is not to write them off.

Having initially failed to qualify for the event, they were handed a spot as the host nation and put into a difficult group with Spain and Kazakhstan, who are both ranked higher than the Britons.

They had also suffered another a blow before the 12-team finals started when Emma Raducanu - the 2021 US Open champion and Britain's highest-ranked player - was ruled out through injury.

After losing to Kazakhstan on Tuesday, they could have been eliminated before even playing Spain on Thursday.

But Spain, led by former world number two Paula Badosa, won 3-0 against Kazakhstan in their opening group match, which then meant Great Britain needed to beat them 3-0 - which they did in a stunning performance that Keothavong described as "something really special".

Watson was brilliant in Thursday's must-win group tie against five-time champions Spain as the hosts reached the last four, but could not reach the same level against an opponent ranked 104 places below her.

Sanders is better than her current ranking of 237 suggests, illustrated by her recent form on the ITF Tour and she has taken that into the BJK Cup Finals this week.

Starting confidently and aggressively, the 28-year-old dominated Watson from the early exchanges and that led to a break for 2-1 in the opening set from which Watson could not recover.

The British number six, backed by noisy support from the biggest crowd of the week, broke for 2-0 in the second set but could not hold on to the lead as Sanders recovered to earn her fifth win of the week.