Stefanos Tsitsipas withdrew from his ATP Cup match against Hubert Hurkacz on Saturday but eased injury fears after playing in the doubles.
The Greek star, ranked fourth in the world, is recovering from elbow surgery but suffered a flare-up of the problem in Sydney and pulled out of the Group D singles tie as a precaution.
With the Australian Open coming up later this month, the two-time Melbourne Park semi-finalist appeared comfortable as he paired up with Michail Pervolarakis for a 6-4 5-7 10-8 win.
"The recovery from my elbow surgery in November is on track for Melbourne and today was a precautionary step to make sure I make Melbourne," he said.
"We will see day by day, match by match until then."
Aristotelis Thanos stepped in for Greece and lost 6-1 6-2 as Hurkacz helped Poland into a 2-0 lead after Kamil Majchrzak had beaten Pervolarakis 6-1 6-4, making the doubles clash a dead rubber.
Spain, runners-up in 2020, showed no mercy on Chile despite the absence of Rafael Nadal as they stormed to a 3-0 win in Group A.
Roberto Bautista Agut downed Cristian Garin 6-0 6-3, while Pablo Carreno Busta defeated Alejandro Tabilo 6-4 7-6 (7-4). Doubles pairing Alejandro Davidovich Fokina and Pedro Martinez battled to a 7-6 (7-3) 4-6 10-7 victory over Tabilo and Tomas Barrios.
Argentina also enjoyed a 3-0 triumph in Group D, with Georgia coming up blank against a team led by Diego Schwartzman.
Serbia, without Novak Djokovic, earned a decisive doubles success to seal a 2-1 win over Norway, with Nikola Cacic and Filip Krajinovic downing Casper Ruud and Viktor Durasovic.