Great Britain, Spain and Ukraine will join hosts China, defending champions Italy and Kazakhstan in September's Billie Jean King Cup Finals after the three nations secured group-stage victories on the penultimate day of the Qualifiers.

Elina Svitolina led Ukraine to a historic first-ever Finals berth with a 6-4, 6-2 win over Switzerland's Jil Teichmann in a tie that her squad eventually won 2-1 to top Group E. Needing just one win to secure a Finals spot, Svitolina rose to the occasion after Marta Kostyuk was upset by 19-year-old Celine Naef -- despite more than 150 places between them in the PIF WTA Rankings. She won the last three games of the first set, and five of the last six, to take the victory.

“I’m very proud of all the team to bring us to the Finals," Svitolina said. "We’ve been waiting so long for this moment, to play there, and try to have a chance to win the World Cup. I knew I had to win to bring us to the Finals, I was trying to focus on one point, one game at a time. I’m very happy with my level and how I hold my nerves.”

In addition to making national history, the win had personal significance for Svitolina. It was her 17th Billie Jean King Cup singles triumph, while equals Elena Tatarkova’s Ukrainian record for most Billie Jean King Cup singles wins.

Nadiia Kichenok and Katarina Zavatska put a bow on the undefeated week by winning their doubles match against Naef and Susan Bandecchi, 6-4, 3-6, [10-5].

Over in The Hague, a deciding doubles win helped lead Great Britain to the Finals for the third time in the last four years, as the unexpected pairing of Katie Boulter and Jodie Burrage delivered a 6-2, 6-2 win over Demi Schuurs and Suzan Lamens to clinch the tie. After the two teams split the singles matches -- Sonay Kartal improved to 2-0 in her Billie Jean King Cup career with a three-set win over Eva Vedder before Lamens upset Boulter in straight sets -- captain Anne Keothavong elected to swap out her originally-nominated team of Harriet Dart and Olivia Nicholls for the decider.

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"You’ve got to take your chances, and for me as captain I had confidence in these two. The way they delivered today seals that," Keothavong said afterwards.

Spain, meanwhile, upset hosts Czechia as both Cristina Busca and Jessica Bouzas Maniero upset higher-ranked foes. Fresh off winning a WTA 250 doubles title in Bogota, World No. 94 Bucsa was a 7-5, 6-1 winner against Marie Bouzkova, ranked No. 58, before first-time BJK Cup player World No. 69 Bouzas Maniero toppled World No. 33 Linda Noskova 6-4, 6-2.

In other Saturday action, a new-look U.S. squad blanked Denmark -- who were without the services of World No. 21 Clara Tauson -- in Group C, setting up a winner-take-all match against hosts Slovakia for one of the two remaining Finals berths. First-time call-ups Hailey Baptiste and Bernarda Pera eased to a pair of singles wins against 19-year-old Rebecca Munk Mortensen and 20-year-old Johanne Svendsen, before Desirae Krawczyk and Asia Muhammad paired for the first time to complete the sweep. Canada faces Japan in Group A action for the other remaining berth.