World number one Sabalenka, from Belarus, defeated American Jessica Pegula, ranked third, in the match played on Friday night.
The final takes place on Saturday evening, Swedish time, where Sabalenka will face either American Coco Gauff, ranked fourth in the world, or Kazakhstan's Jelena Rybakina, ranked second.
28-year-old Sabalenka won last year's US Open, but has had a tough year behind her, including a recent exit in the fourth round of the WTA tournament in Cincinnati.
