Six-time Grand Slam semi-finallist Tim Henman, left, is captaining the Great Britain team in SydneyCameron Norrie and Katie Swan gave Great Britain the perfect start to their United Cup campaign as their victories contributed to a 2-0 lead over Australia in Sydney.
World number 14 Norrie confidently saw off Alex de Minaur, ranked 10 places below him, with a 6-3 6-3 win.
Swan broke serve in her first three return games en route to a 6-4 6-3 win over world number 772 Zoe Hives.
Harriet Dart can win the tie if she beats Ajla Tomljanovic on Friday.
Dan Evans will then face Jason Kubler on Friday, ahead of a doubles match in which Evans and Dart take on Sam Stosur and John Peers.
The inaugural mixed-team tournament involves six round-robin groups of three teams.
Spain will compete against Great Britain and Australia for a chance to play either the United States, Germany or the Czech Republic in a play-off to reach the semi-finals.
The event, which is being played across three cities in Australia, has pulled in some big names with Rafael Nadal lining up for Spain and world number one Iga Swiatek representing Poland, but there are also some high-profile absentees.
Australian number one Nick Kyrgios pulled out of the tournament a day before its start as he prioritised overcoming an injury ahead of the Australian Open, while Britain's former US Open champion Emma Raducanu has chosen to play in a WTA event in Auckland instead.
Norrie (right) had given Great Britain a winning startNorrie, 27, said the event gave him a high-intensity start to the season.
"I'm feeling great," he said. "Especially first match of the year, there's a lot of nerves. No tougher task than to play 'Demon' [Alex de Minaur] in Australia. It was not easy.
"I ran a lot, I absolutely drenched three shirts. I really enjoyed the atmosphere - and nice to get the win."
Swan proved too consistent for Hives and, after falling 3-0 down in the second set, swept back to win the next six games and the match.
"I haven't played for about two and a half months so I was pretty nervous coming out, but what a way to start the year," said the 23-year-old.
"Such a cool event. It's a great start for the team and I'm looking forward to supporting the guys playing tomorrow."
