Argentina and Chile both secured important victories on night three as their attention now shifts to their final ties on Wednesday.
World No. 11 Denis Schwartzman had the opportunity to complete a singles sweep against Greece but entered a heavy underdog against Stefanos Tsitsipas on Ken Rosewall Arena on night three.
The Argentinian found himself down a set and a break after the opening game of the second set but was able to wrestle back control of the match shortly after.
Tsitsipas, who missed his first singles match of the ATP Cup due to elbow soreness, showed glimpses of his best but the consistent Schwartzman ultimately prevailed 6-7(5), 6-3, 6-3.
The Argentinian remarked post-match that he thought a long match could be the undoing of his opponent.
“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,” Schwartzman said.
The testing conditions and time on court will have certainly tested out Tsitsipas’ elbow before Greece does battle again on Wednesday against Georgia.
Earlier, World No. 44 Federico Delbonis opened proceedings with a 7-6(5), 6-1 triumph over Greece’s Michail Pervolarakis.
Delbonis overcame a 2-4 deficit in the first set tiebreak and never looked back from there, breaking his opponent twice in the second to emerge victorious in 93 minutes.
Post-match the Argentinian heaped praise on the tactics of Pervolarakis.
“Michail impressed me a lot. Especially in the first set when he tried to push his backhand to my forehand and on every forehand… I was a bit uncomfortable with that,” Delbonis said.
“But I took that first set. I am very happy to take a bit of the pressure off Diego.”
Argentina will now do battle with Poland on Wednesday in what is a mouth-watering tie that will decide the winner of Group D.
Meanwhile, at Qudos Bank Arena, Serbia and Chile were involved in a tie of their own that was decided by a doubles rubber.
Serbia’s singles win came courtesy of Filip Krajinović who came through a hard-fought match against World No. 139 Alejandro Tabilo 6-4, 3-6, 7-6(5).
Krajinović found himself up a set and a break at the beginning of the second set but found himself feeling the pressure and that was all Tabilo needed to catch fire.
The Chilean immediately broke back and sent the match to a third thanks to a barrage of winners that saw him wrestle back the momentum.
The final set saw plenty of momentum swings but Krajinovic’s 6-2 lead proved a bridge too far for Tabilo to overcome.
Post-match, Krajinović lamented the pressure that Serbian players face in Djokovic’s absence and admitted that it played a part in his set two struggles.
"I got tight, which is normal when you play for your country,” Krajinović said.
“At the end, he came up with some big serves and I'm very proud to have won. It means a lot to start the year well.”
Chile’s Cristian Garin was then able to survive a physically taxing affair against Dusan Lajovic to send the tie to a doubles decider.
The Chilean was leading 4-6, 6-4, 3-0 against Lajovic when the Serbian retired after two hours and 14 minutes citing cramps.
Post-match Garin was sympathetic toward his opponent in the aftermath of such a gruelling contest.
"We played an amazing match and I feel sorry for Dusan," Garin said.
“It was so tough.”
The all-important doubles rubber was a seesawing affair that ultimately saw Chile emerge victorious 6-4 3-6 [10-7]
Serbia was represented by a combination of Nikola Cacic and Matej Sabanov but it was the Tomas Barrios Vera and Alejandro Tabilo pairing that proved too strong.
In ATP Cup action at Ken Rosewall Arena on Wednesday, Germany takes on the United States before Canada meets Great Britain.
At Qudos Bank Arena, Italy will face France in the day session before Russia and Australia battle to likely decide who will emerge from Group B.