"If I'm being really frank, I just feel like I had like the worst attitude today," the 21-year-old Osaka said. "I feel like I didn't really know how to cope with not playing well."
She dropped two service games in the first and went down an early break in the second but had chances to get even in the sixth game, when she had two break points but committed a string of unforced errors and Tsurenko held for 4-2.
Osaka kicked the air at one point and dropped her racket to the court after missing another, before visibly questioning how she could be getting it so wrong when her forehand skewed wide on game point.
"I was sulking a little bit, and like there are moments that I tried not to do that. But then the ball wouldn't go in, and then I would go back to being like childish and stuff," Osaka said. "So I think like that was sort of my main problem today.
"I feel like last year I did a lot of that, and I'm trying to change it more, and I think I have — like toward the end of last year. Hopefully this isn't like a recurring thing."
Japanese flags were still waving in the crowd at Pat Rafter Arena for the next match, when No. 2-seeded Kei Nishikori defeated Jeremy Chardy 6-2, 6-2 in 66 minutes.
"Felt very good physically and, tennis-wise, I think it was perfect," Nishikori said.
He'll play fourth-seeded Daniil Medvedev, a 7-6 (6), 6-2 winner over Jo-Wilfried Tsonga, in Sunday's final, where he's hoping to claim his first title since Memphis in 2016.
Tsurenko is 4-0 in finals, and is hoping to extend that streak when she takes on No. 5-seeded Karolina Pliskova, who beat Donna Vekic 6-3, 6-4 in the night semifinal.
Tsurenko had lost both previous encounters to Osaka, including their U.S. Open quarterfinal.
From 15-40 down in the ninth, Osaka saved two match points with aces, got the advantage with an audacious drop shot and then held with an ace to ensure Tsurenko had to serve out.
Tsurenko went on the attack, earned another two match points with a volley winner and clinched it with the second of those.
She has grown in confidence since her trip to the U.S. Open quarterfinals, and is playing with more aggression.
"I don't want to say that this was my best tennis, but it was quite a high level," Tsurenko said. "I feel I can kind of handle every kind of pressure on court now, even when someone like Naomi is playing really strong."
Osaka is having to deal with different expectations now.
"Before, I would just be nervous to be there in a way, and now I feel nervous because I think I should win ... and I feel like people expect me to win," she said. "So that's like an added amount of nerves. But, I mean, I feel like I'm getting used to it."
Osaka will continue her preparations for the Australian Open, which starts Jan. 14 in Melbourne, with an emphasis on trying to not to sulk when things are going wrong.
"In a way this experience for me is better than winning the tournament, because like this helpless feeling I have, I think today I learned sort of what I ... I can do to like improve the situation," she said. "There aren't many moments that I feel like that. But, yeah, I feel like today was a very valuable lesson."
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