Naomi Osaka said she was driven by the fear of letting her teammates down after helping Japan take control of their Billie Jean King Cup qualifier against Kazakhstan on Friday.
The former world number one and four-time major winner beat Yulia Putintseva 6-2, 7-6 (7/5) in Tokyo to give Japan a commanding lead after team-mate Nao Hibino had beaten Anna Danilina 6-1, 6-0 earlier in the day.
Osaka, who returned to tennis late last year after giving birth, said she was "super-nervous" about playing in Japan for the first time since appearing at the Pan Pacific Open in September 2022.
She soon found her rhythm in the match, hitting 15 aces and no double faults.
"I'm the kind of person that I don't like to disappoint people," said Osaka, who is playing at the Billie Jean King Cup for the first time since 2020.
"I feel like I came here to do a job and obviously I want to do well.
"It would probably devastate me a lot more to lose here than it would to lose in a regular tournament, just because I want to support everyone as much as they support me."
Osaka, whose world ranking has risen from 831 to 193 since she began her comeback, won the first set comfortably against world number 50 Putintseva.
She rattled off three straight aces to start the second set but she found her opponent a tougher nut to crack as the match wore on.
Osaka was also at one point interrupted by a child making noise as she prepared to serve.
She calmly waited for the child's mother to resolve the situation and said she was reminded of her own daughter Shai.
"I thought it was really cute but I also felt really bad because I saw the mom and she looked really flustered," said Osaka.
"I just wanted her to take her time and relax."
Osaka will face world number 939 Danilina on Saturday unless Hibino has already wrapped up victory for Japan in her reverse singles match against Putintseva.
World number 79 Hibino needed just 57 minutes to beat Danilina.
"I watched the first set of Nao's match in the audience and I just thought the atmosphere was really incredible," said Osaka.
"I didn't want to be the one to let the energy go down so I probably did have a lot of extra motivation."
