Local favorite Kurumi Nara's hopes of reaching the quarterfinals of the Japan Women's Open were shattered on Thursday with a straight-sets defeat to Chinese "wall" Wang Qiang.

World No. 57 Wang broke 108th-ranked Nara five times in a dominant display en route to a 6-2, 6-3 win in 68 minutes at Ariake Tennis Forest Park, securing a meeting in the last eight with Croatian surprise package Jana Fett.

"My opponent played well today," said Nara. "I didn't play badly but I was unable to break my way through the thick wall she put up and my lobs weren't working."

Nara shocked Japanese No. 1 Naomi Osaka in the first round on Wednesday, but the 25-year-old made a nervous start against Wang and failed to win a single point on her serve in the first game.

Wang broke again to take a 5-2 lead as Nara sprayed a return wide and closed out the first set with her third ace of the match.

Wang had Nara chasing lost causes with pinpoint ground strokes and delicate backhand slices and went 2-1 up and then 4-3 ahead on Nara's serve in the second set.

A wayward backhand return from the serving Nara handed Wang the victory.

"Naomi (Osaka) plays with more pace and that kind of game is easier to deal with, but today's opponent was more accurate with her shots and it was difficult to predict where she was going to place them."

Nara said Wang had improved considerably since the last time the two met, when Nara won 6-1, 6-3 in Kaohsiung, Taiwan last year.

"The last time we played she made more mistakes and I remember it being a bit easier to read her shots. She is more solid now and makes fewer mistakes."

"She selected her shots with a bit more time today and I was too slow to respond," said Nara.

Wang said of Nara, "She is a good player and good at the baseline. From last year to this year I have improved a lot. I play more aggressively now."

Qualifier Fett, who stunned top-seeded Frenchwoman Kristina Mladenovic in the first round, booked her spot in the last eight with a 6-0, 6-3 win over Slovakian Jana Cepelova.

American Christina McHale stayed on course to defend her title, thrashing Spain's Sara Sorribes Tormo, 6-1, 6-1. McHale next faces Belgian third seed Elise Mertens.

"It was tougher than the score shows and there were some close games, but I love playing here in Tokyo and I am happy to be back in the quarterfinals," said McHale.

"I've never played her (Mertens) before but I know she is playing very well. We practiced the other day together and it's going to be a tough match, but I am looking forward to playing," she added.

In the day's opening match, Kazak qualifier Zarina Diyas produced a shock, beating Chinese second seed Zhang Shuai 6-4, 6-2. Diyas faces eighth-seeded compatriot Yulia Putintseva in the last eight.

Putintseva advanced after her Chinese opponent Han Xinyun retired in the second set with Putintseva leading 6-2, 2-0.

Japan's title hopes now rest with 171st-ranked Miyu Kato, who reached the quarterfinals on Wednesday and will be up against Serbia's Aleksandra Krunic.