Qualification for the tournament is based on the ATP ranking of each country's top-ranked singles player, while Australia qualifies by virtue of a host wildcard. Hopefully, I'll be better for Thursday. We have a strong team, all the to @pablocarreno91 @BautistaAgut & @M-Granollers #vamos'.
De Minaur was scheduled to take on world No.2 Nadal on Tuesday night, but the 20-time grand-slam victor withdrew just before the tie started with a stiff lower back.
Spanish number two Roberto Bautista Agut will now face de Minaur, while John Millman takes on Pablo Carreno Busta in the opening rubber.
The pair beat Shapovalov and Milos Raonic 7-5, 7-6 (7-4) as the defending champions took the tie 2-1 in Group A.
Having pushed Djokovic to five sets in the Australian Open final last year, Thiem is among the top contenders looking to dethrone the Serb at the year's opening Grand Slam.
With the score tied at 1-1 after the two singles matches, Berrettini backed up his impressive performance to claim the doubles alongside countryman Fabio Fognini, 6-1, 6-4, against Thiem and Dennis Novak.
Afterwards, the world No1 said of his singles win: "It was a very close match. I hope all of you who came here enjoyed it because I certainly did", the world No. 1 told a small crowd at the stadium, soaking up boisterous cheers from Serbian fans. Andrey Rublev powered through Argentina's Guido 6-1, 6-2, before 2020 Nitto ATP Finals champion Daniil Medvedev overcame Diego Schwartzman 7-5, 6-3, to secure the win for Russian Federation.