Cameron Norrie and Katie Boulter ensured Great Britain made a winning start at the United Cup with victory over hosts Australia in Perth.
British men’s number one Cameron Norrie won a third-set tie-break to defeat Alex de Minaur 6-4 2-6 7-6 (7-2).
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.
Boulter and team-mate Neal Skupski face Storm Hunter and Matthew Ebden in the concluding mixed doubles later on Friday as they aim to strengthen their bid to progress by completing a clean sweep.
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.
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