MELBOURNE, Australia -- No.4 seed and reigning US Open champion Naomi Osaka of Japan executed a marvelous comeback over Grand Slam upset specialist Hsieh Su-wei of Chinese Taipei in the third round of the 2019 Australian Open on Saturday, winning 5-7, 6-4, 6-1, to reach the round of 16 in Melbourne for the second straight year.

"I'm happy with how I fought," Osaka said in her post-match press conference. "For me, that's, like, one of the biggest things I always thought I could improve."

Osaka needed to rebound from a set and a 4-1 down before eventually squeaking past 28th-seeded Hsieh in one hour and 57 minutes. The first-ever Grand Slam champion representing Japan emerged victorious thanks to 41 winners, including eight aces. Osaka also had 42 unforced errors, but nearly half of those came in the first set, as she cleaned up her game as the match wore on.

Dangerous Hsieh has three Top 10 wins in her career, and each one has come at a Grand Slam event in the past two years. Last year, Hsieh knocked off then-World No.3 Garbine Muguruza en route to the round of 16 in Melbourne, ten full years after she reached the same stage for the first time as a qualifier. But she fell to 0-2 lifetime against Osaka despite a valiant effort.

"I walked into the match knowing that [Hsieh] was going to do a lot of strange things, no offense," Osaka said with a smile. "But she was just playing so well, and I think I got overwhelmed."

"Then after a while, I just started thinking that I'm in a Grand Slam," Osaka added. "I shouldn't be sad, I'm playing against a really great player, so I should just enjoy my time and try and put all my energy into doing the best that I can on every point."

Next up for Osaka in the fourth round will be No.13 seed Anastasija Sevastova of Latvia, who defeated 21st-seeded Wang Qiang of China, also on Saturday.

"I have played [Sevastova] like two weeks ago in Brisbane," Osaka said. "That match was very tough. She's a really great player. I want to say I think we played three times now, so we know each other's games quite well. I know for sure that match is going to be hard. I played three sets against her last time and she beat me in straight sets the time before that. So definitely it's going to be a really big fight for me."

A topsy-turvy opening set was in the offing from the very start, as the raw power of Osaka mixed with the forward-moving guile of Hsieh to produce entertaining yet unpredictable results. The Japanese star had a chance to take an early break at 1-1, but missed a return into the net on her break point, allowing Hsieh to hold for 2-1.

This seemingly proved costly when Hsieh drew first blood in the set, taking advantage of numerous errors from Osaka’s backhand to break serve and lead 4-2. But Osaka used her frustration to kickstart her game while the errors from Hsieh mounted, and the fourth seed picked off three games in a row to lead 5-4 and serve for the set.

But Osaka stumbled with more miscues as Hsieh resumed her wizardry at the net, and the player from Chinese Taipei claimed a hard-earned break on her third point of the game to level the set at 5-5. Hsieh held on for 6-5, forcing Osaka to serve to stay in the first set.

Another back-and-forth game ensued as Osaka fended off two set points with her power game -- the first with an error-forcing forehand and the second with an ace. But Hsieh was running everything down at this point, and at the end of a rally, Osaka flew a backhand wide to give Hsieh a third set point. There, Hsieh moved up to net to put away a forehand and force another error to take a one-set lead.

Hsieh maintained her momentum at the start of the second set, using tremendous defense to chase down everything Osaka sent her way, and wrested a service break at 2-0 on her fifth break point of a marathon game. Hsieh held onto her break lead all the way to 4-1.

But, like the first set, Osaka found a purple patch from a dire position. Serving at 4-2, Hsieh led 40-0, but the Japanese player recovered a dominant patch of form off her forehand to blast her way to five straight points and a break, putting her back on serve at 4-3.

Osaka had to stave off a break point with a backhand winner down the line in the next game, but from that point forward in the set, she took control. A strong serve set up a forehand winner for the 4-4 hold, and she broke for 5-4 with another error-forcing forehand, putting her in the same position as she was in the first set.

This time, however, Osaka would make no mistakes. Even a tumble over her ankle could not stop the runaway train, as she used her booming serve to clinch her fifth straight game and tie up the match at one set apiece.

The final set was all Osaka, as she crushed 14 winners to only six unforced errors. Meanwhile, Hsieh's serve lost its potency in the decider, as she won just 10 of 24 service points. Osaka broke at love in the opening game via a stellar backhand crosscourt pass, and after a tough hold at 3-1 and claiming a second service break at to lead 4-1, the No.4 seed cruised to another fourth-round showing in Melbourne.

"Of course it gives me confidence to be able to win like this," Osaka summed up. "I was two games from losing the match, so I think being able to come back and fight is something that I have been attempting to do for a while, but I haven't really been able to grasp, like, the emotions to do it. So winning like this gives me confidence."