Britain’s Harriet Dart beat Maddison Inglis in straight sets to seal the team’s victory over Australia in the United Cup.
Day one wins for Cameron Norrie and Katie Swan meant Britain was already 2-0 on their group opponents.
Inglis was called up late for the game after Ajla Tomljanovic withdrew with a knee injury.
Dart’s 6-4, 6-4 win on Friday meant Great Britain were victorious with two games to play.
Dan Evans lost to Jason Kubler 6-3 7-6 (7-3) and Evans and Dart will meet in a doubles match later Friday.
Great Britain will now prepare to face their other group opponents Spain, with the opener being played between Norrie and Rafael Nadal on Saturday.
Swan will face Nuria Parrizas-Diaz on the same day.
The first mixed team tournament features six round robin groups of three teams.
Great Britain, Spain and Australia are vying for a chance to face the USA, Germany or the Czech Republic in a play-off to reach the semi-finals.
Meanwhile Nick Kyrgios has accused Australia co-captain Lleyton Hewitt of ‘throwing him under the bus’.
Kyrgios withdrew from the United Cup mixed team tournament in order to be fit for the Australian Open and his co-captain’s public response left the 27-year-old frustrated.
Hewitt said he was unaware of Kyrgios’ withdrawal and was frustrated by the lack of communication.
After Tomljanovic pulled out of her match against Dart, Kyrgios tweeted to wonder if she would receive the same treatment.
“Mmm I wonder if Sam Stosur [Australia’s co-captain] go throw her under the bus like our captain did for me… ‘hard to prep when you don’t know what’s going on’,” he wrote.