Shuko Aoyama and Eri Hozumi took Japan into the Billie Jean King Cup quarterfinals for the first time since 2013 on Thursday with a stunning comeback win over Romania.
Aoyama and Hozumi defeated Elena-Gabriela Ruse and Monica Niculescu 6-1, 7-5 in the deciding doubles to set-up a last-eight clash with Italy on Saturday.
The Japanese pair, who won their first WTA Tour title in Tokyo last month, saved nine out of the 10 break points they faced.
Japan had got off to the worst possible start in their first round clash with the Romanians when Nao Hibino lost 6-2, 6-4 to Ana Bogdan. It was Bogdan's fifth win in six career meetings against Hibino.
However, California-born Ena Shibahara, playing singles in place of the injured Naomi Osaka, made light of her 135 world ranking to defeat 73rd-ranked Jaqueline Cristian 6-4, 7-6 (7/2) to level the tie.
"It's an amazing feeling," admitted Shibahara. "I was a little nervous going into the match but I just took that opportunity to challenge myself and do the best that I can to keep my team in the match."
The result justified Japan captain Ai Sugiyama's decision to name Shibahara in singles ahead of the higher-ranked Moyuka Uchijima.
"I feel great," said Sugiyama who has now won all eight of her ties since taking over as skipper last year.
"To get to the Finals was one of my goals and all the players and staff put in a great effort. When I was playing, it was tough for me to play team events. I put too much pressure.
"But these days the girls are dealing with the pressure and are playing really well."
In the second match of the day, Slovakia stunned 18-time champions United States 2-1 after also dropping the first rubber.
Renata Jamrichova, just 17 and ranked a lowly 375, went down 7-5, 6-4 to experienced Taylor Townsend, the world number 69.
However, 43rd-ranked Rebecca Sramkova then levelled the tie by seeing off world number 11 Danielle Collins 6-2, 7-5.
Viktoria Hruncakova and Tereza Mihalikova then claimed the deciding doubles thanks to a 6-3, 3-6, 10-8 win over Ashlyn Krueger and Townsend.
Their win was sealed on a seventh match point as 2002 champions Slovakia booked a quarter-final clash with Australia.
The season-ending showpiece in Malaga had got underway a day later than scheduled after Wednesday's action was postponed following a weather warning in the wake of recent devastating floods in Spain.