Swiatek off to flying start as Poland beat Brazil in season-opening United Cup
Swiatek ended last season with 11 straight wins to lift the China Open and WTA Finals trophies and reclaim the top spot from Aryna Sabalenka, and she showed no signs of rust against Haddad Maia in a rematch of their French Open semi-final.
She cruised through the opening set in typically dominant style and went up 4-1 in the next after an early wobble on serve, before ending WTA Elite Trophy champion Haddad Maia's seven-match winning streak.
Swiatek said she hoped to be stronger in the new year after enjoying the most "peaceful" off-season in a long time.
"In 2020 I won my first slam so it was all pretty hectic. I wasn't focusing on tennis and the right things. I needed to get back on the right path," Swiatek said.
"After 2021 I changed coaches, so a different challenge. Last year I felt like the whole world was watching. I feel like I've gotten used to this kind of position. I could really just focus on practising and resting."
Hurkacz handed Brazil their second defeat in Group A of the $10 million tournament featuring 18 countries when he defeated Thiago Seyboth Wild 6-7(4), 6-2, 6-3.
The Netherlands beat Norway 2-1 in Sydney as captain Wesley Koolhof and Demi Schuurs defeated Casper Ruud and Ulrikke Eikeri 7-6(5), 7-5 in the mixed doubles decider.
Ruud earlier levelled up the Group F tie at 1-1 beating Tallon Griekspoor 6-3, 6-4 with an aggressive performance after Arantxa Rus gave the Dutch a fast start getting past Malene Helgo 7-6(4), 6-1.
"That's the goal," former world number two Ruud said of his plans for a bolder approach in the 2024 season.
"Last year I was too defensive, running too much."
Defending champions the United States will be in action against Britain on Sunday before Novak Djokovic begins his final preparations for a tilt at an 11th Australian Open title when Serbia play China.
Zhang Zhizhen warmed up for his encounter against the world number one with a 5-7, 6-3, 6-4 win over the Czech Republic's Jiri Lehecka before Zheng Qinwen settled the Group E tie by stunning Wimbledon champion Marketa Vondrousova 6-1, 2-6, 6-1.
Germany also beat Italy 2-1 as Alexander Zverev overcame Lorenzo Sonego 6-7(5), 6-3, 6-4 before partnering the returning Angelique Kerber to down Sonego and Angelica Moratelli 6-3, 6-0.
Jasmine Paolini earlier shook off cramps to earn a 6-4, 7-5 win over Kerber, who played her first singles match in 18 months after a maternity break and is preparing for the opening Grand Slam of 2024 starting on January 14th.