Australia won a crucial lead at the start of the Davis Cup with Bosnia and Herzegovina, thanks to John Millman.
The world number 36 has never won the best national ranking and world number 52 Damir Dzumhur in two attempts, but beat him 6-3 6-2 to open the scoring five games.
Millman's strong 12 months included a run for the quarter-finals of the US Open, during which he defeated Roger Federer in four sets.
Australia's No. 1 Alex de Minaur, ranked 28th in the world ranking, will now face Mirza Basic, number 99 in the world, in the second individual game.
Australia wants to be among a dozen world cup winners this weekend with 24 selections – the winners adding up to six automatic qualifiers in the Cup final in Madrid at the end of November.
The Australians criticized the changes in the format of the cup – eliminating draws at home and reducing games to the three sets in two days, instead of the traditional five-setters over three days.
On Saturday, John Peers and Jordan Thompson will face Tomislav Brkic and Basic in doubles before the simple reverse games – which Australia coach Lleyton Hewitt expects to be dead rubber to date.
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The Australians are without the talented but controversial pair Nick Kyrgios and Bernard Tomic.
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– with AAP