Japan's Naomi Osaka reacts after losing against France's Caroline Garcia during their women's singles match on day two of the Australian Open tennis tournament in Melbourne on Jan 15, 2024. (PHOTO / AFP)

MELBOURNE, Australia - Naomi Osaka's much-anticipated comeback to Grand Slam tennis on Monday was cut short by Caroline Garcia at the Australian Open, while former finalists Stefanos Tsitsipas and Daniil Medvedev battled through tough first-round matches.

All eyes in the night session at Melbourne Park were focused on new mother Osaka, who stepped away from the sport in Sept 2022 due to mental health concerns.

Osaka fought hard and showed glimpses of the form that powered her to four Grand Slam titles before falling to a focused Garcia 6-4, 7-6 (2) in 86 minutes.

The 26-year-old Osaka enjoyed strong crowd support in her long-awaited comeback, but could not sustain the pressure against an assured Garcia.

Naomi Osaka of Japan plays a backhand return to Caroline Garcia of France during their first round match at the Australian Open tennis championships at Melbourne Park, Melbourne, Australia, on Jan 15, 2024. (PHOTO / AP)

Reigning US Open champion and fourth seed Coco Gauff brushed aside unseeded Anna Karolina Schmiedlova 6-3, 6-0 to win her sixth straight match of the season.

There is much expectation on the 19-year-old American, who is bidding to become the first women's player in five years to win the US Open and Australian Open back-to-back.

"I think I did well returning and then I found my serve towards the end," said Gauff, who hit 15 winners. "She's a tough player to play but I'm happy with how I was able to manage my emotions today."

ALSO READ: China's Zhang roars into AO 2nd round for first time

Sixth seed Ons Jabeur also cruised in her comprehensive 6-3, 6-1 victory over Ukrainian qualifier Yuliia Starodubtseva.

Wimbledon champion Marketa Vondrousova crashed out after a 6-1, 6-2 defeat to qualifier Dayana Yastremska in 76 minutes.

France's Caroline Garcia serves against Japan's Naomi Osaka during their women's singles match on day two of the Australian Open tennis tournament in Melbourne on Jan 15, 2024. (PHOTO / AFP)

The world number seven was completely outplayed by an aggressive Yastremska of Ukraine, who is ranked 93 having reached a career high of 21 in 2020.

It was the latest disappointment for the 24-year-old Vondrousova at Melbourne Park, where she has never progressed past the fourth round.

Men's seventh seed Tsitsipas started slowly against Belgian lucky loser Zizou Bergs before storming to a 5-7, 6-1, 6-1, 6-3 win.

Tsitsipas was supposed to play former Wimbledon finalist Matteo Berrettini, but the Italian withdrew with an injury.

ALSO READ: Djokovic survives scare as Sabalenka sparkles at AO

The 129th-ranked Bergs stepped up in his place and he proved no pushover, but Tsitsipas turned things around to reach the second round in Melbourne for the sixth straight year.

Greece's Stefanos Tsitsipas serves against Belgium's Zizou Bergs during their men's singles match on day two of the Australian Open tennis tournament in Melbourne on Jan 15, 2024. (PHOTO / AFP)

"I was very focused, especially after losing the first set," Tsitsipas said, "I knew that this is my time to change things up and move on with better tennis...with better power and movement on the court."

"I think I outplayed him as well physically. I was stronger physically today, at least that's the way I felt."

Third seed Medvedev was pushed hard by qualifier Terence Atmane in hot daytime conditions before the teary-eyed Frenchman retired from the match with cramps.

Medvedev, a two-time tournament finalist, had wrested control after losing the first set before Atmane was unable to continue when trailing 5-7, 6-2, 6-4, 1-0.

Daniil Medvedev of Russia plays a forehand return to Terence Atmane of France during their first round match at the Australian Open tennis championships at Melbourne Park, Melbourne, Australia, on Jan 15, 2024. (PHOTO / AP)

"The conditions were brutal," said former US Open champion Medvedev. "I'm just happy to be through. I played bad at the beginning in the first set, but I was happy I could regain momentum."

ALSO READ: Djokovic aims Australian Open win with 'pain-free' wrist

Chinese top men's player Zhang Zhizhen lifted his level in the key moments to prevail against Federico Coria 6-4, 7-6 (3), 7-6 (5).

Zhang, ranked number 54, will face Ugo Humbert in the second round.

Zhang Zhizhen of China hits a return during the men's singles first round match between Zhang Zhizhen of China and Federico Coria of Argentina at Australian Open tennis tournament in Melbourne, Australia, Jan 15, 2024. (PHOTO / XINHUA)

Australia's main hope Alex de Minaur, the 10th seed, was left relieved after former number three Milos Raonic retired mid-match due to a hip injury with the contest locked at one set apiece.

Grand Slam champions Andy Murray and Stan Wawrinka were knocked out.

"It's a definite possibility that will be the last time I play here," said former number one Murray after he fell to Argentina's Tomas Martin Etcheverry in straight sets.

Women's top-ranked player Iga Swiatek will start her campaign for a first Australian Open title on Tuesday, so too will men's second seed Carlos Alcaraz.

READ MORE: Djokovic plays qualifier, Swiatek faces Kenin at Australian Open

Zheng Qinwen, China's highest-ranked women's player, opens her tournament against American Ashlyn Krueger.