Naomi Osaka of Japan hits a return against Daria Saville of Australia during their women's singles match on day two of the Pan Pacific Open tennis tournament in Tokyo on Sept 20, 2022. (PHILIP FONG / AFP)

Naomi Osaka's title defence at her home Pan Pacific Open ended on Thursday when the former world number one withdrew ahead of her second-round match against Beatriz Haddad Maia due to abdominal pain.

"I am really sorry that I am not able to compete today," said the four-time Grand Slam champion, who won the tournament when it was last held in 2019 in her hometown of Osaka.

ALSO READ: I won't become a tennis ghost, says Federer, ahead of final bow

"It's an honor to be able to play at the Toray Pan Pacific Open in front of the amazing fans here in Japan. This has and always will be a special tournament for me and I wish I could have stepped on court today, but my body won't let me."

It was the latest setback for the 24-year-old, who sat out the entire grasscourt season with an Achilles injury and also retired from her first-round match in Toronto with a back problem in the leadup to the US Open.

Brazil's Haddad Maia will face either fourth seed Veronika Kudermetova or Mexican qualifier Fernanda Contreras Gomez in the quarter-finals.