The escalating action on Wednesday (starting Tuesday night in the U.S.) unfolds at four far-flung venues in four different time zones.

The United Cup quarterfinals get underway at the RAC Arena in Perth with Poland-China, followed by Australia-Serbia.

No fewer than six major champions are in play at the Brisbane International, while Amanda Anisimova returns to the court in Auckland. 

Let’s get right to it:

Brisbane: Osaka-Pliskova

Throughout her career, Karolina Pliskova has always stoically played on -- “even though I had, like, broken everything.”

Last year, at the age of 31, she decided to step away after playing in Guadalajara in mid-September. She went back to the Czech Republic, healed both mentally and physically, and spent time with her twin sister Kristyna and her baby.

Pliskova returns to the Hologic WTA Tour on Wednesday with a high-profile match in the Brisbane International -- against returning mother Naomi Osaka.

“I was not away for that much,” Pliskova told WTA Insider. “For me, it went so quickly. Feeling quite OK. First tournament of the year. I don’t have any crazy expectations.”

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But being a three-time Brisbane champion, that might not quite be true.

“Here I won three times, so it’s difficult to say I just came here to win first round,” Pliskova said, laughing. “I try to keep it low, but of course I still want to win tournaments and go deep in the draw.”

Pliskova holds a 3-2 head-to-head edge, winning the last meeting four years ago in Brisbane in three sets.

Osaka's top winners from her comeback match in Brisbane

“We had some really good matches in the past,” Pliskova said. “Difficult for both of us. This match to start, it can be a good test for me, her as well.”

In addition, it’s the first 2024 outing for Aryna Sabalenka and Elena Rybakina. The No.1-seeded Sabalenka plays Lucia Bronzetti and No.2 Rybakina takes on Aussie qualifier Olivia Gadecki. Both are first-time matches.

Auckland: Anisimova back in action

No.5 seed Marie Bouzkova takes on returning wild card Amanda Anisimova in what looks like a compelling second-round match.

Bouzkova was a winner in three sets over Magdalena Frech, while Anisimova won her first match in eight months, 7-5, 6-4 over Anastasia Pavyuchenkova. The 22-year-old Anisimova -- a 2019 semifinalist at Roland Garros -- stepped away from tennis last May, citing concern for her mental health.

In other action, No.3 Lesia Tsurenko plays Diane Parry, while No.4 seed Emma Navarro meets Elina Avanesyan.

United Cup: Perth

Group A winner Poland meets Group E runner-up China, while Group C winner Australia meets Group E winner Serbia.

For Australia, it’s a powerful homefield advantage. It was evident Monday when Storm Hunter and Matthew Ebden teamed up to defeat Jessica Pegula and Rajeev Ram in the mixed doubles decider. That put the Aussies into the quarterfinals.

“I think it definitely helped us,” Storm Hunter said. “Obviously knowing that we're locals, it's kind of like us taking on the world, which was pretty cool. Yeah, we just wanted to do everybody proud.”

Australia will send out Ajla Tomljanovic against Olga Danilovic of Serbia. They have never played.

“She’s a great player, tough opponent,” Danilovic said of Tomljanovic. “They are a complete team, so it’s going to be a tough battle. But I think we proved two times now that we are a team, and we play as a team and we win as a team.”

Poland features World No.1 Iga Swiatek against Zheng Qinwen, in a terrific early-season matchup. Both players are 2-0 so far Down Under, but Swiatek holds a 4-0 head-to-head edge -- but three of the four meetings have gone the three-set distance.

“I’m really happy with my level and the way I’m focused,” Swiatek said. “I’m not feeling rusty. I’m not feeling like I need to get into a lot of rhythm. I’m playing freely, the same way I felt in Beijing, after US Open basically. I’m just happy to be in that place.”

Schedule of play

RAC Arena: 10 a.m. start
H. Hurkacz (POL) vs Z. Zhang (CHN)
I. Swiatek (POL) vs Q. Zheng (CHN)
I. Swiatek (POL) / H. Hurkacz (POL) vs Q. Zheng (CHN) / Z. Zhang (CHN)

Not Before 5 p.m.
A. de Minaur (AUS) vs N. Djokovic (SRB)
A. Tomljanovic (AUS) vs O. Danilovic (SRB)
S. Hunter (AUS) / M. Ebden (AUS) vs O. Danilovic (SRB) / N. Djokovic (SRB)

United Cup: Sydney

In the definitive tiebreak against Germany, the French crowd was singing as Caroline Garcia and Edouard Roger-Vasselin defeated Angelique Kerber and Alexander Zverev.

“It’s very far from home,” Garcia said. “So it’s always great, already great to have the bench behind us, because they were really cheering out very loudly. It’s great fun. It’s why I believe I play tennis, but I believe we also play tennis for that, to leave great emotion out there.”

Wednesday features the last day of round-robin ties, France-Italy and Greece-Canada. France and Canada, both 1-0, can lock down quarterfinal berths with wins.

For France, it’s Caroline Garica versus Jasmine Paolini. Garcia has won four of five matches, but they split in 2023 -- in Lyon and Zhengzhou.

Meanwhile, Maria Sakkari of Greece takes on Leylah Fernandez. Sakkari has won both previous matches, most recently last year in Washington, D.C.

Norway became the Group F champion and advanced to the quarterfinals Tuesday when Croatia defeated the Netherlands 2-1.

Schedule of play

Ken Rosewall Arena: 10:30 a.m. start

Adrian Mannarino (FRA) vs. Lorenzo Sonego (ITA)
Caroline Garcia (FRA) vs. Jasmine Paolini (ITA)
Followed by mixed doubles

Not before 5:30 p.m.

Stefanos Tsitsipas (GRE) vs. Felix Auger-Aliassime (CAN)
Maria Sakkari (GRE) vs. Leylah Fernandez (CAN)
Followed by mixed doubles