Former U.S. Open champion Marin Cilic had too much experience for No. 448-ranked Kacper Zuk, setting up Croatia's victory over Poland with a 7-6 (8), 6-4 win at the ATP Cup on Monday.
Two-time Grand Slam finalist Kevin Anderson led South Africa to a victory over Chile in Group A at Brisbane, keeping his team in contention for the playoffs despite an opening loss to Serbia, and Japan clinched its second straight win with victory in both singles matches against Georgia in Perth.
Cilic, who has a career-high ranking of No. 3 but slipped to 38 after an injury-shortened 2019 season, has now won both his singles matches in Sydney at the new international men's team event.
Zuk was making his tour-level debut but tested Cilic, who was only able to convert one of his 13 break point chances.
Hubert Hurkacz beat Borna Coric 6-2, 6-2 to split the singles results, but Croatia pair Ivan Dodig and Nikola Mektic clinched the encounter with a 6-2, 6-1 win in the doubles over Hurkacz and Lukasz Kubot.
"If I have to pick some things that I need to do better, it's just converting breakpoints. I had a lot of them," Cilic said. “Otherwise, I felt that the level was quite good.”
Croatia leads the Group E with two wins from two ahead of Argentina's night match against Austria in Sydney.
Anderson, who is coming off a six-month injury layoff and pushed Serbia's Novak Djokovic in two tight sets on the weekend, outclassed Cristian Garin 6-0, 6-3 after Lloyd Harris' 6-4, 6-4 victory over Nicolas Jarry. The South African doubles combination made it a 3-0 sweep.
Anderson said the goal was now to win the last round of the group stage to have a chance of reaching the quarterfinals, which start Thursday in Sydney.
“We had to get a win today, so we were able to do that,” Anderson said. "Some of it is out of our hands as well, already having, well, taking the loss against Serbia.
“We'll bring back our full intensity for our match against France in a couple days time.”
Japan followed up its 3-0 sweep against Uruguay with a win over Georgia, with Go Soeda beating Aleksandre Metreveli 4-6, 6-3, 6-2 and Yoshihito Nishioka beating Nikoloz Basilashvili 6-2, 6-3.
Serbia was playing France later Monday in Brisbane, with Spain against Uruguay in Perth.