DAY 4 at the ATP Cup saw plenty of ups and downs, with the gap narrowing as nations look to head into the Final Eight. Serbia cemented their spot, joining Australia in the next stage of the tournament, while star players continued to prove their dominance across the board. A further 144 aces were hit on Day 4, making for another boost in donations for the Australian bushfire relief, with the total exceeding $70k not even halfway through the tournament.

Group A:
South Africa 3 defeated Chile 0
Kevin Anderson (RSA) defeated Cristian Garin (CHI) 6-0 6-3
Lloyd Harris (RSA) defeated Nicolas Jarry (CHI) 6-4 6-4
Klaasen/Roelofse (RSA) defeated Garin/Jarry (CHI) 1-6 6-3 [10-7]

South Africa impressed against Chile in the singles, collecting two straight sets wins with both Kevin Anderson and Lloyd Harris dominating in their respective matchups. In the doubles it was a different story, with Raven Klaasen and Ruan Roelofse only winning one game in the first set against Cristian Garin and Nicolas Jarry, before working their way back into the match with a solid second set to take the match to a tiebreaker, eventually winning the tie 10-7 despite the best efforts of Garin and Jarry.

Serbia 2 defeated France 1
Benoit Paire (FRA) defeated Dusan Lajovic (SER) 6-2 6-7 6-4
Novak Djokovic (SER) defeated Gael Monfils (FRA) 6-3 6-2
Djokovic/Troicki (SER) defeated Mahut/Roger-Vasselin (FRA) 6-3 6-7 [10-3]

A doubles win from Novak Djokovic and Viktor Troicki pushed Serbia over the line against France to win the tie 2-1, with France putting up a tough battle to head into a tiebreaker after winning back the second set before running out of puff against the Serbian duo. Frenchman Benoit Paire got over the line against Dusan Lajovic, dropping a close second set before coming out on top in the third to give France a look in over the dominant nation. Djokovic was too good however, with the 16-time grand slam victor dominating ninth ranked Gael Monfils, 6-3 6-2. This victory sends Serbia into the Final Eight as only the second country to do so after two rounds.

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Group B:
Japan 2 defeated Georgia 1
Yoshihito Nishioka (JPN) defeated Nikoloz Basilashvili (GEO) 6-2 6-3
Go Soeda (JPN) defeated Aleksandre Metreveli (GEO) 4-6 6-3 6-2
Bakshi/Tkemaladze (GEO) defeated McLachlan/Matsui (JPN) 6-2 6-4

A slow start from Go Soeda saw Georgia get a look in with Alexandre Metreveli in control early, before Soeda upped his form to take back the match, eventually winning the second and third sets comfortably, 4-6 6-3 6-2. Yoshihito Nishioka was far too good against Nikoloz Basilashvili, winning in straight sets to continue his impressive form, having not dropped a set across the tournament so far. Georgian doubles pair, Alexandre Bakshi and Zura Tkemaladze won back some confidence defeating Japan in straight sets, 6-2 6-4, but it was not enough to win the tie given the prowess of Nishioka and Soeda.

Spain 3 defeated Uruguay 0
Roberto Bautista Agut (ESP) defeated Franco Roncadelli (URU) 6-1 6-2
Rafael Nadal (ESP) defeated Pablo Cuevas (URU) 6-2 6-1
Carreno Busta/Lopez defeated Behar/Fumeaux (URU) 6-1 3-6 [10-3]

Roberto Bautista Agut got Spain off to a stellar start against Uruguay, dominating the contest against youngster Franco Roncadelli in straight sets, only dropping three games in the 6-1 6-2 win. World number one Rafael Nadal continued in similar fashion against Pablo Cuevas with the same scores but reversed with a 6-2 6-1 victory. Spain rounded out its solid form with a doubles win but was certainly challenged more by the combination of Ariel Behar and Juan Fumeaux, who were slow to get into the match, dropping the first set with only one game in their pocket, before working their way to a tiebreaker after dominating the second set.

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Group E:
Croatia 2 defeated Poland 1
Marin Cilic (CRO) defeated Kacper Zug (POL) 7-6 6-4
Hubert Hurkacz (POL) defeated Borna Coric (CRO) 6-2 6-2
Dodig/Mektic (CRO) defeated Hurkacz/Kubot (POL) 6-2 6-1

A confident start from Croatia kept the ball rolling despite dropping the second match, with Marin Cilic challenged by Kacper Zug in the first set before catching a break in the second to reign supreme, 7-6 6-4. It was another story entirely in the second match between Borna Coric and Hubert Hurkacz, with Hurkacz dominating the contest 2-6 3-6 and not allowing Coric a look in. Things did not quite go to plan for Hurkacz and teammate Lucasz Kubot in the doubles however, with the pair going down to Ivan Dodig and Nikola Mktic in straight sets.

Austria 3 defeated Argentina 0
Dennis Novak (AUT) defeated Guido Pella (ARG) 0-6 6-4 6-4
Dominic Thiem (AUT) defeated Diego Schwartzman 6-3 7-6
Marach/Melzer (AUT) defeated Gonzalez/Molteni 6-1 6-4

Austria made amends for its first few days in the tournament with a straight win over Argentina. Dennis Novak put in the hard yards to fight back against Guido Pella after dropping the first set without winning a single game. Novak blitzed the second and third sets, eventually going on to win 0-6 6-4 6-4 against the 25th ranked player. Dominic Thiem was challenged by Diego Schwartzman in the second set, almost taking the match to a third before Thiem took back control to win 6-3 7-6. In the doubles, Oliver Marach and Jurgen Melzer never looked like losing, downing Maximo Gonzalez and Andres Molteni in straight sets.