NINGBO, China -- Karolina Muchova secured the last spot at the season-ending WTA Finals after Marta Kostyuk retired from her second-round match at the Ningbo Open on Wednesday.

Kostyuk retired following a medical timeout after losing the first set 6-4 to Ekaterina Alexandrova.

The WTA Tour had said Kostyuk needed to reach the final in Ningbo to stop Muchova, who is not playing this week, from clinching the spot for the Nov. 8-15 finals in Indian Wells, Calif.

Reaching the finals is another landmark moment for Muchova in 2026 after she made the Wimbledon final against Linda Noskova and then teamed up with Noskova to win the Billie Jean King Cup for the Czech Republic.

Iga Swiatek was also in contention for the finals spot until she withdrew from the Ningbo tournament with a thigh injury and said she was ending her season early.

The other players qualified for the finals are Elena Rybakina, Aryna Sabalenka, Mirra Andreeva, Jessica Pegula, Coco Gauff, Elina Svitolina and Noskova.

Alexandrova moves on to a quarterfinal match in Ningbo with Leylah Fernandez after the Canadian beat Aliaksandra Sasnovich 7-5, 6-7 (3), 6-3 to pick up her 11th win in her last 14 matches.

Also Wednesday, Sara Bejlek upset eighth-seeded Sorana Cirstea 7-6 (3), 6-4. She sets up an all-Czech quarterfinal match with Marie Bouzkova, who won 7-5, 6-2 against Anastasia Zakharova.