One day after Japanese qualifier Aoi Ito scored an upset against No.8 seed Elisabetta Cocciaretto to reach the Kinoshita Group Japan Open quarterfinals, her compatriot Sara Saito followed suit. The 18-year-old wild card also took out a seed to notch her first career Top 50 win, defeating No.5 Elina Avanesyan 7-6(2), 6-4 after saving two set points in the first set.

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The success of Saito and 20-year-old Ito, the two youngest Japanese players in the draw, is noteworthy for several reasons. Both are making their tour-level debuts this week. The last time a WTA quarterfinal lineup featured two players contesting their first main draw was all the way back at Marbella 2010, when qualifiers Simona Halep and Beatriz Garcia Vidagany both made the last eight.

It's also a promising sign for the future of Japanese tennis. This week marks the first time in five years two Japanese players have reached the quarterfinals of a tournament. In 2019, eventual champion Naomi Osaka and Misaki Doi both featured in the final eight in Osaka. And it's been 28 years since a quarterfinal lineup featured two under-21 Japanese players -- when 20-year-olds Miho Saeki and Yuka Yoshida both made that stage of Pattaya 1996.

Saito and Ito play contrasting styles of tennis. Ito's unorthodox mix of slices and finesse was inspired by Hsieh Su-Wei. Saito is the more conventional of the pair, with her neat groundstroke technique and superb redirections of pace on show against Avanesyan in what she described afterwards as "a perfect match."

On WTA debut, qualifier Ito upsets Cocciaretto to make Osaka quarters

Both had marked themselves out as ones to watch ahead of their breakthroughs this week. Saito is a former junior No.2 who reached three girls' doubles Grand Slam finals in 2023, and she has cut her ranking from No.364 at the start of the year to No.179 this week. Ito was ranked No.420 this time last year, and is now at No.188.

And they're not alone. Japanese juniors have been thriving recently. Sayaka Ishii, 19, and Ena Koike, 17, were also ranked in the junior Top 10 last year. When Ishii made her own WTA main-draw debut in August as a qualifier in Cleveland, she also turned heads by holding three match points on Katerina Siniakova before falling 6-7(5), 6-3, 7-6(5). Wakana Sonobe, 16, became the first Japanese girl to reach a junior singles Grand Slam final since 2010 at the US Open last month.

A slew of upsets in Osaka means that only one seed, No.7 Diane Parry, has made the quarterfinals. Five players who came through qualifying -- four qualifiers and one lucky loser -- are in the last eight, an Open Era first. Opportunity knocks, especially for Saito and Ito, who are just one round away from setting the first all-Japanese semifinal on the Hologic WTA Tour since San Diego 2005, when Ai Sugiyama defeated Akiko Morigami via retirement. On Friday, Saito will take on qualifier Kimberly Birrell, while Ito faces lucky loser Eva Lys.