Former world number one Osaka, now ranked 73, defeated Lucia Bronzetti of Italy 6-3, 6-2 in the first round of the WTA 1000 China Open with the Frenchman Mouratoglou in her players’ box.
The 26-year-old Osaka split from Belgian coach Wim Fissette this month as she attempts to return to the form that propelled her to the top of the women’s game.
Japan’s Osaka said she “felt like I needed a change” and described Mouratoglou, who is best known as Williams’ long-time former coach, as “a big person”.
“I like the way he coaches. I think it’s going to be really interesting,” she said in Beijing after setting up a second-round meeting with 21st seed Yulia Putintseva of Kazakhstan.
“I think I’m at a stage in my life that I don’t want to have regrets. I’d rather pull the trigger on something and I don’t want to say ‘fail’, but I feel like I really need to learn as much as possible in this stage of my career.
“Patrick seemed like the guy with I guess the information that I wanted to learn from.”
Fissette had two stints coaching Osaka, from 2019 to the summer of 2022 and again when they reunited last year as Osaka launched her return to tennis after the birth of her daughter Shai in July 2023.
Osaka has struggled to put together victories since she returned to the WTA Tour in January.
She bowed out in the second round of the recent US Open and her best results since returning to action have been two quarter-final appearances.
Osaka, who won the China Open in 2019, admitted being a little wary initially about Mouratoglou, given the 54-year-old’s long and successful association with the legendary Williams.
“I think the fact that he was Serena’s coach for me made me want to avoid him just because his persona is so big,” she said.
“Then I met him, talked to him, worked with him on the court. He absolutely is a really good coach. I’m really glad that he’s taking this project on as well.”
Osaka said she was “still a little nervous around him”.
“I kind of look to the floor when he looks at me. I think I do need a lot more time to spend together with him,” she said.
“I’m getting a little more comfortable day by day.”