Naomi Osaka was unable to clinch her first title in front of Japanese fans on Sunday, losing in straight sets to Karolina Pliskova in the Toray Pan Pacific Open final.

After reaching the tournament decider without dropping a set, the world No. 7's run of dominance at Arena Tachikawa Tachihi ended in a 6-4, 6-4 loss to the eighth-ranked Czech.

The 20-year-old Japanese had been gunning for her third WTA title this year following victories at the BNP Paribas Open in March and the U.S. Open earlier this month.

Undaunted by the partisan crowd, the 26-year-old Pliskova was willing to mix it up with the hard-hitting home favorite from the outset, riding her own powerful serve and ground strokes to victory.

The winner of April's Porsche Tennis Grand Prix in Stuttgart said her accurate service game had been the key to claiming her 11th WTA crown in Tokyo.

"My serve is one of my biggest weapons. Even when it's not working, I know it can work the next day," said former world No. 1 Pliskova, who praised third-seeded Osaka for her play throughout the tournament.

"Naomi was playing so good the whole tournament, the future is bright. She's a good player, but I'm just happy with my performance this time in Tokyo."

In the third WTA meeting between the pair, Osaka looked to stamp her authority early, sending down a pair of aces on the way to winning the opening game in just 1 minute, 14 seconds.

[Getty/Kyodo]

Her serve wavered in the fifth game, however, allowing Pliskova to win the first break point of the match and take a 3-2 lead.

Seeking to break back, Osaka hit a number of impressive winners against Pliskova's serve, but the fourth seed held firm to close out the set.

In the second set, both players rode their serves early, with Osaka winning love games in the third and fifth games before Pliskova returned the favor in the sixth to tie the scores 3-3.

Down 0-30 in the ninth game, Osaka tossed her racket in frustration before giving Pliskova break point with a forehand over the baseline. The Czech seized the opportunity, coming to the net to hit a forehand winner and take a 5-4 lead.

Pliskova then served out the match with a love game, sealing the victory with an ace.

In her postgame press conference, Pliskova said she had been wary of Osaka's power and had tailored a game plan aimed at neutralizing the U.S. Open champion's dangerous forehand.

"I didn't want to try to overpower her because I think she just has more power than me, so I just wanted to be patient and just to wait for my chances, waiting for my shots," Pliskova said.

"I was just trying to serve well, to mix the speed a little bit (and) play lots to her backhand. She was missing quite a lot today and it was working, so I didn't change anything."

Both players now turn their attention to the next round on the WTA's Asian swing, the Wuhan Open in China.

Osaka, however, indicated she might pull out of the tournament in order to recover from her grueling recent schedule.

"I've literally never felt more tired in my entire life, so I kind of want to say the chances of me playing in the next tournament are very low," she said. "But I still haven't talked to everyone yet. That's sort of like me playing ahead, but I'm still not 100 percent sure yet."