Naomi Osaka's first tournament as a mom ends in a loss to three-time winner Karolina Pliskova in Brisbane

BRISBANE, Australia (AP) — A loss didn't bother Naomi Osaka at the Brisbane International as much as the missed opportunity for more matches ahead of the Australian Open.

The four-time major winner's first tournament since becoming a mother ended in a 3-6, 7-6 (4), 6-4 second-round loss Wednesday to three-time Brisbane International champion Karolina Pliskova.

Osaka won her first match at the elite level since late 2022 on Monday in straight sets against Tamara Korpatsch.

After that win, she said the birth in July of her daughter, Shai, and the changes to her mindset since becoming a mother had given her a better perspective on tennis.

A second-round encounter featuring two former No. 1-ranked players was a step up in tempo and a better indication of how Osaka's preparations are going for the Australian Open, the year's first Grand Slam event, starting Jan. 14 in Melbourne.

"The week is definitely shorter than I wanted it to be," Osaka said. "I feel like I'm pretty good where I am right now. Even the last time I played her, I think I played better today."

Osaka won the first set but Pliskova recovered and fired 16 aces and hit 50 winners, saving 10 of the 12 breakpoint chances she faced and making amends for her 11 double-faults.

"I saw the stats after and my break points could have been better," Osaka said, "but I think other than that we both played really well ... so hopefully she says the same thing!"

A former finalist at Wimbledon and the U.S. Open now ranked 39th, the 31-year-old Pliskova was playing for the first time since September after a left wrist injury curtailed her 2023 season.

"A lot of things to improve, but a good start," said Pliskova, who had her left wrist and hand taped for the opening match of the day on Pat Rafter Arena.

She'll next play third-seeded Jelena Ostapenko, who beat Camila Giorgi 6-1, 6-4.

Top seed and defending Australian Open champion Aryna Sabalenka had a 6-3, 6-0 win over Lucia Bronzetti and will face Zhu Li, a 1-6, 6-3, 7-6 (7) winner over Danielle Collins, in the Round of 16.

Second-seeded Elena Rybakina, the 2022 Wimbledon champion, had a 6-4, 6-1 win over Olivia Gadecki and will next play No. 13 Elise Mertens, who beat 2017 U.S. Open champion Sloane Stephens 2-6, 6-1, 6-3.

On the men's side, top-seeded Holger Rune beat Alexander Shevchenko 6-4, 5-7, 6-2 in the night match to advance to a quarterfinal against Australian qualifier James Duckworth. Fourth-seeded Ugo Humbert had a 6-4, 6-4 win over Alex Michelsen in a first-round match.

Osaka's next match will be an exhibition in Melbourne on Rod Laver Arena, the main court for the Australian Open, next week.

She was happy with her serve against Pliskova, firing 14 aces and just two double-faults, and winning 83% of points when she got her first serve into play.

"I've trained so hard since giving birth, I need to enjoy these moments," Osaka said, adding she's changed her attitude to winning and losing since becoming a mom. "I do feel different. I mean, of course I feel sad, but the sadness is me being like, 'Aww, I wish I could have done better, because I know I'm spending so much time away from her (Shai), so I want it to be worth it somehow."

Competing in Brisbane proved that all her practice wasn't a waste ahead of the Australian Open, where she has won two of her Grand Slam titles.

"For me even stepping on the court is a personal win because a couple of weeks ago I was even doubting if I could play with everyone," she said. "So I guess these two matches that I've had kind of prove to me that I am doing OK, and the year is just going to get better for me."