Japan's Mai Hontama was unable to capitalize on a golden opportunity to upset world No. 10 Barbora Krejcikova of the Czech Republic in the first round of the Australian Open on Sunday.

Krejcikova fought back to win 2-6, 6-4, 6-3 on the opening day of the Grand Slam tournament at Melbourne Park. The 122nd-ranked Hontama led 4-3 in the second set before losing the next three games, two of them on her serve.

Both players struggled to hold serve as they grabbed six breaks each to remain neck and neck.

Among other Japanese players, Nao Hibino lost quickly to Greece's Maria Sakkari, the No. 8 seed, 6-4, 6-1.

On the men's side, 20-year-old Shintaro Mochizuki, making just his second main draw appearance at a Grand Slam, played a competitive opening against Czech Tomas Machac but ultimately fell in straight sets, 5-7, 1-6, 5-7.

Two-time Australian Open champion Naomi Osaka is scheduled to play her first-round match Monday night against France's Caroline Garcia.

Osaka gave birth to her first child, a daughter, last July and is set for her first Grand Slam appearance since the 2022 U.S. Open.