Stefanos Tsitsipas is confident he will be close to full fitness for this month's Australian Open after battling through his first major test at the ATP Cup in Sydney on Monday.

The world number four noted some pain during his 6-7 (5) 6-3 6-3 defeat to Diego Schwartzman in his first singles match since withdrawing from last year’s ATP Tour finals and undergoing elbow surgery.

His defeat, despite leading by a set and a break, hastened a 3-0 loss for Greece against Argentina and while Tsitsipas is unsure about competing in his next match on Wednesday, he is more positive about his Australian Open chances from 17 January.

The two-time Melbourne semi-finalist told the official tournament website: "It was good to see myself perform at such a level. I didn’t expect it.

"It worked out better than I thought. I was able to hit balls that I was scared to hit two weeks ago, so I’m heading towards the right direction.

"It gets better and better every single day almost. We have plenty of time before the Australian Open begins, and I think if I take the right precautions and follow what my doctor says, then I can see myself performing at 100 per cent at the Australian Open."

Hubert Hurkacz (Poland) beat Aleksandre Metreveli (Georgia)

Federico Delbonis beat Michail Pervolarakis, while Maximo Gonzalez and Andres Molteni beat Markos Kalovelonis and Petros Tsitsipas as Argentina set up a Group D decider against Poland on Wednesday.

The Poles overcame Georgia 3-0 after Hubert Hurkacz avoided a major upset against world number 571 Aleksandre Metreveli, a replacement for Georgian number one Nikoloz Basilashvili, rallying for a 6-7 (5) 6-3 6-1 win.

Kamil Majchrzak beat Alex Bakshi while Szymon Walkow and Jan Zielinski paired to see off Bakshi and Zura Tkemaladze in the dead doubles rubber.

Spain made it two wins out of two in Group A as they swept Norway aside 3-0, with Roberto Bautista Agut sealing victory with a 6-4 7-6 (4) win over Norwegian number one Casper Ruud.

Pablo Carreno Busta got Spain off to a winning start by beating world number 345 Viktor Durasovic, before Alejandro Davidovich Fokina and Pedro Martinez saw off Lukas Hellum-Lilleengen and Andreja Petrovic in the doubles.

Chile edged past Serbia 2-1 after Tomas Barrios Vera and Alejandro Tabilo squeezed out Nikola Cacic and Matej Sabanov 6-4 3-6 10-7 in the decisive doubles rubber.

Filip Krajinovic had given Serbia a winning start with victory over Tabilo, but Dusan Lajovic was forced to withdraw injured when he trailed Chilean number one Cristian Garin 4-6 6-4 3-0 in the second doubles clash.