World number four Stefanos Tsitsipas is hopeful he will be “performing at 100% at the Australian Open”.
Greece’s Tsitsipas was beaten 6-7 (5-7) 6-3 6-3 by Argentine Diego Schwartzman at the ATP Cup in Sydney in his first singles match since elbow surgery.
Tsitsipas, 23, was “in a lot of pain” after playing in the doubles on Saturday, but after Monday’s loss he was only “in a little bit of pain”.
The Australian Open starts on 17 January in Melbourne.
“That is enough [time to recover], I believe,” he said. “But I haven’t had [this kind of injury] before, so I don’t know.”
He added: “I think if I take the right precautions and follow what my doctor says, then I can see myself performing at 100% at the Australian Open.”
Tsitsipas won the first set against Schwartzman, before the 29-year-old rallied to win the match and secure victory for Argentina.
Earlier, his team-mate Federico Delbonis beat Greece’s Michail Pervolarakis 7-6 (7-5) 6-1.
“I was just trying to think that it was his first match for two months after his elbow [injury], so I was thinking just to try and be in the match,” said Schwartzman.
“I had the chance and I think I was ready. I am very happy because playing against Stefanos and being a set and a break down is not easy, but I found a way.”
Argentina went on to win the doubles to clinch a 3-0 victory and will face Poland on Wednesday in their final group D match with a place in the semi-finals up for grabs, after Poland beat Georgia 3-0.
World number nine Hubert Hurkacz, from Poland, recovered from a set down to beat Georgia’s Aleksandre Metreveli, the world number 570, 6-7 (5-7) 6-3 6-1.
Pablo Carreno Busta and Roberto Bautista Agut won their respective singles ties in straight sets to ensure victory for Spain over Norway.
Bautista Agut upset Norwegian world number eight Casper Ruud 6-4 7-6 (7-4) after Carreno Busta had beaten Viktor Durasovic 6-3 6-3.
Chile beat Serbia 2-1 after Marcelo Tomas Barrios Vera and Alejandro Tabilo gave them a 6-4 3-6 10-7 victory in the deciding doubles.
The score was tied at 1-1 after the singles rubbers, with Serbia’s Dusan Lajovic forced to retire injured from his match with Cristian Garin with the Chilean winning 4-6 6-4 3-0, after team-mate Filip Krajinovic defeated Tabilo 6-4 3-6 7-6 (7-5).
