OSAKA, Japan -- No.1 seed Naomi Osaka made a winning debut in her city of birth, as the Japanese No.1 moved past Bulgarian qualifier Viktoriya Tomova, 7-5, 6-3, to book a spot in the Toray Pan Pacific Open quarterfinals.

"I was very nervous playing this match, because I felt like I really wanted to win," Osaka told the press, after the match. "After I won, I felt relieved, and also, I guess, happy with certain parts of how I was playing."

Photos: A decade of champions at the Pan Pacific Open: From Sharapova to Pliskova

"I always feel better here," Osaka added. "Of course, there’s always going to be a feeling of pressure, but for me, I don’t feel pressure from the city that I’m in, I feel pressure from the position -- from me, not the location. So that’s never really a factor for me."

World No.4 Osaka is aiming for her first Toray Pan Pacific Open title after finishing as runner-up in 2016 (losing to Caroline Wozniacki) and last year (falling to Karolina Pliskova), when the event took place in Tokyo. After a challenging start where she fell behind two early breaks, Osaka pulled out the victory over World No.181 Tomova in an hour and a half.

Former World No.1 Osaka finished the tilt with 40 winners, including 13 thundering aces, to 27 unforced errors, and converted five of her eight break points. Tomova, who was facing a Top 20 player for the first time in her career, hung with Osaka for the entirety of the encounter, and also held eight break points, but converted two fewer than her two-time Grand Slam-winning opponent.

"I know in the first set, I just started slow, and then in the second set, I just made a lot of really bad decisions in the first game," Osaka stated. "Other than that, I knew that I was the power player, and that I was the one that was kind of dictating how the match would go. It gave me a little bit of comfort knowing that if I just dialed down my unforced errors, I was going to win."

Tomova started the match well out in front, claiming a break in the first game after Osaka let a 40-15 lead slip due to errors. The Bulgarian qualifier saved a break point before consolidating for 2-0, then earned another break point in the next game with a deft dropshot. Osaka double faulted on that occasion, and the top seed was down a swift double-break to the qualifier at 3-0.

Methodically, Osaka began to pull herself into the match, grasping one break back with a backhand crosscourt winner, and erasing two break points in the next game with powerful groundstroke winners to reach 3-2. Osaka found her targets with her fearsome forehand en route to break points at 4-3, and she got level for the first time by slamming a putaway off of that side.

Osaka began to find her rhythm on serve, slamming three aces in her next two service games to reach 6-5. Serving to stay in the opening stanza, Tomova was undone by errors, ceding triple set point to the top seed. The Bulgarian double faulted right away, and Osaka had escaped with a one-set lead after facing a difficult deficit.

Osaka let a 40-0 lead slip in the opening game of the second set, and the combatants fought through a seven-deuce game before Tomova once again earned an early break, polishing off that tussle with a backhand return winner down the line. However, Osaka reached parity more quickly in this particular go-around, finding a perfect forehand pass down the line to level the set at 2-2.

After a hold at love to lead 4-3, Osaka found her opportunity to take command after an error-riddled game from Tomova, where the qualifier double faulted to drop serve at love and cede a 5-3 lead to the No.1 seed.

Osaka did not falter at the finish line, and found a forehand winner to reach double match point. Osaka then fired an additional forehand winner to pass the tough test she received from Tomova, winning 12 of the last 13 points in the process.

In the quarterfinals, Osaka could potentially face a difficult assignment in the form of Yulia Putintseva of Kazakhstan: Putintseva is 3-0 against Osaka, including two wins on the grass of Wimbledon and Birmingham earlier this year. Putintseva faces Russian qualifier Varvara Flink in the second round on Thursday.

"Looking into the next matches, in general, I just 100 percent need to improve my first-serve percentage," said Osaka. "It wasn’t great today; honestly, it hasn’t been great since Cincinnati. I feel like I definitely need to improve that."