WIMBLEDON, Great Britain -- No.18 seed Naomi Osaka of Japan reached the third round of Wimbledon for the second straight year on Thursday, following a straightforward victory over British wild card Katie Boulter, 6-3, 6-4.

"I had to fight really hard for this match," Osaka told the media, during her post-match press conference. "I think [Boulter] played really well. I mean, as a whole, I'm pleased with how I played, but also I want to improve a lot of things."

In their only prior meeting, Osaka dispatched Boulter 6-1, 6-2 on grass at the Nature Valley Classic in Birmingham two weeks ago, and although the British up-and-comer acquitted herself even better on Thursday, it was another straight-set win for the World No.18, who claimed her first WTA title at the BNP Paribas Open in Indian Wells in the spring.

"I was nervous today, but I don't think it was because she was a crowd favorite," said Osaka. "For me it was more, like, I beat her recently, so I felt like I needed to back that win up again. I got a little bit tight in the beginning and towards the end. I'm just glad that I was able to pull it out."

In a high-quality battle, Osaka blasted 24 winners, including four aces, to Boulter's 17 winners. Osaka could only get 59 percent of her first serves in on the day, but when she did, it was lethal, winning 83 percent of points during the 78-minute encounter. 

Osaka is now 8-1 in second-round matches at Grand Slams, and will try her hand at another third-round tilt when she takes on No.11 seed Angelique Kerber, the 2016 Wimbledon finalist and former World No.1. Kerber overcame Claire Liu, the American qualifier and last year's Wimbledon junior champion, in three sets on Thursday.

"I think [Kerber] does a lot of things good," Osaka mused. "She runs really well. She returns really well. I can't really say there's anything she does bad. I feel like she was No. 1 in the world and won two Grand Slams, so for sure she's going to be a very hard opponent to play against."

Osaka says the key against Kerber, "since she's such a great mover, [is] just staying really calm and accepting if she makes a really good winner or if I make a mistake. Because playing against her, you have to expect long rallies because she doesn't really miss."

"I feel like I've been in the third round [of Grand Slams] a lot," Osaka stated. "I feel like that's a good thing, but also I don't want to just stop in the third round every time. I want to keep going. I've only, like, went past the third round once. I would like to, like, go higher and higher."

Boulter gave Osaka quite a shock to start, using excellent service returns to garner four break points throughout the opening game. But, eventually, Osaka found her highly praised service prowess to blast her way to a hold, and the 20-year-old Japanese star seemed to be well on her way to an easy day after breaking an error-prone Boulter for 2-0.

However, the 21-year-old Brit stayed strong, and after falling behind 3-0, Boulter took advantage of a patch of thin serving by Osaka to break serve and claw her way back on serve at 3-2. But Osaka did not panic, and immediately regained her break advantage, moving Boulter around the court and finishing points with powerful groundstrokes en route to 4-2.

As long as Osaka’s first serve was clicking, the Japanese player was difficult to overcome, winning 81 percent of those points. In the final game of the set, Osaka rebounded from 0-30, hitting a backhand winner to reach set point, then slamming a forehand to close out the opening frame. Osaka had 11 winners to only three unforced errors in the set.

In the second set, Boulter again heavily challenged Osaka in the Japanese player’s opening service game, holding three break points, but Osaka once again powered through, holding for 1-1. Osaka eventually claimed the only break of the set at 2-2 after Boulter pushed a backhand miscue into the net.

Osaka had no problems maintaining that break advantage, holding with ease throughout the rest of the match. At 5-4, a powerful forehand forced an error from Boulter to set up double match point. On the first opportunity, Osaka fired one final great serve, and slammed a forehand winner off the return to clinch victory.