MELBOURNE, Australia (AP) — Moments after her Grand Slam comeback ended in a first-round loss, Naomi Osaka put her gold jacket on and walked back through the players' tunnel where her name has a prominent place among recent Australian Open champions.

Three matches into her return from 15 months off the tour, and six months after the birth of her daughter, Shai, Osaka lost 6-4, 7-6 (2) to 16th-seeded Caroline Garcia in a tight encounter at Rod Laver Arena on Monday night.

"The competitive in me is really frustrated that I’m not winning these matches, of course," Osaka told a post-match news conference. "So I wouldn’t say, like, this comeback is how I thought because I’m delusional enough to think I could have won the tournament."

She smiled at that point, and added: "I think my delusion is what allows me to win the tournaments."

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Osaka won the U.S. Open in 2018 and 2020, and the Australian title in 2019 and '21. This was the first time she lost in the first round in Melbourne, where she made her debut in 2016.

She took time out from tennis for her own wellbeing after first-round exits at the French Open and U.S. Open in 2022. She's not planning any more breaks for now.

"Yeah, I think I just have to keep living day by day and training hard and playing a lot more matches," she said. "And hopefully my dreams will come true."

The big-serving Garcia didn't give Osaka a look at a breakpoint in the match. Most of the rallies were short − only three longer than nine shots. The bulk were less than four. Most of the service holds were comfortable − except for Osaka's one dropped game in the first set. That was all the difference.

"I have a lot of respect for Naomi as a person and as a player − 15 months she’s been away," Garcia said. "I'm very glad to see her back. Six months after giving birth, she’s playing quite amazing already. We have to watch out."

Osaka was one of three past Australian Open champions who returned to play at Melbourne Park for the first time as moms, joining 2016 winner Angelique Kerber and 2018 champion Caroline Wozniacki.

In the opening match on Rod Laver, U.S. Open champion Coco Gauff needed just 60 minutes to advance.

Gauff, with increased confidence in her serve thanks to some advice from Andy Roddick, began her bid for back-to-back Grand Slam singles titles with a 6-3, 6-0 victory over Anna Karolina Schmiedlova.

The 19-year-old American, who won her first major at the U.S. Open in September, said she was a little nervous to start.

"I think I did well returning, then I found my serve toward the end (of the set)," she said. "When I was nervous at 3-3, I told myself: ‘I feel good, I look good, so just have fun’. That was able to relax me a little bit’."

Gauff dropped just one point on her serve in the second set and credited Roddick, saying "he’s probably one of the best servers in history."

Wimbledon champion Marketa Vondrousova didn’t make it past the first round, losing 6-1, 6-2 to Dayana Yastremska and struggling with a hip injury.

A third 16-year-old reached the second round, with Mirra Andreeva beating 29-year-old Bernarda Pera 7-5, 6-2 to set up a second-round match with sixth-seeded Ons Jabeur, a three-time runner-up at Grand Slams.

Alina Korneeva and Brenda Fruhvirtova, both also 16, advanced after their first Grand Slam main draw wins on Sunday.

"I’m really excited for this," Andreeva said about playing Jabeur. "I said many times before that, she’s the player that I was looking up to. I really like the way she plays her game and I’m sure it’s going to be a great match."

Australia’s newest top-10 player, Alex de Minaur, advanced after a truncated night match on Rod Laver Arena. He was leading 2016 Wimbledon finalist Milos Raonic 6-7 (6), 6-3, 2-0 when the big-serving Canadian retired from the match with an injury.

Third-seeded Daniil Medvedev, the 2021 and 2022 finalist at Melbourne Park and at last year’s U.S. Open, also advanced when his opponent retired from their match.

Medvedev had dropped the first set but was leading 5-7, 6-2, 6-4, 1-0 when the 22-year-old Terence Atmane quit because of cramps.

"When I was feeling tired in the third set, I looked up the other end and saw he was cramping," Medvedev said. "The conditions were fine but it has not been hot these seven days and then it was hot today, so you get more stressed."

Stefanos Tsitsipas, who lost last year’s Australian final to Novak Djokovic, advanced with a 5-7, 6-1, 6-1, 6-3 win over Zizou Bergs.

Stan Wawrinka, the 2014 Australian Open champion and three-time Grand Slam winner, was beaten 6-4, 3-6, 5-7, 6-3, 6-0 by Adrian Mannarino. That left 10-time winner Djokovic as the only Australian champion left in the men’s draw.

Five-time Australian Open finalist Andy Murray lost to Tomas Martin Etcheverry 6-4, 6-2, 6-2 and said it might be the last time he contests the season’s first major.