Cameron Norrie and Katie Boulter ensured Great Britain made a winning start at the United Cup with victory over hosts Australia in Perth.

Boulter then secured her nation's opening win with a match to spare by beating Ajla Tomljanovic 6-2 6-4.

GB face the United States - winners of the inaugural tournament in January - in their final Group C match on Sunday.

World number 18 Norrie, 28, dominated the decisive tie-break to earn a hard-fought win over the 12th-ranked De Minaur after two hours 23 minutes - his first victory over a top-20 opponent in his past 10 attempts.

Boulter, Britain's top-ranked women's player, took charge from the outset against Tomljanovic, racing into a 4-0 first-set lead on her way to an assured straight-set win which gave GB an unassailable 2-0 advantage.

However, GB were unable to complete a clean sweep of wins later on Friday as Boulter and team-mate Neal Skupski lost 6-3 7-6 (7-5) to Storm Hunter and Matthew Ebden in the concluding mixed doubles match.

GB reached the quarter-finals of the tournament's inaugural edition in January, where they were beaten by eventual winners - and upcoming opponents - the USA.

At the United Cup, which takes place from 29 December to 7 January, countries compete in a round-robin format across six groups of three.

The six group winners, plus the best-performing runner-up in the two host cities Perth and Sydney, advance to the quarter-finals.