Defending champion Johanna Larsson came through an all-Swedish first-round match against Rebecca Peterson in the Ericsson Open on Tuesday, while third seed Kiki Bertens crashed out.
Larsson beat Mona Barthel to claim the solitary WTA singles title in her career and the eighth seed remains in the hunt to retain her crown after ousting wildcard Peterson 7-6 (7-3) 6-2 on home soil.
The Boden-born world number 82, who also won the doubles title in Bastad last year, will face qualifier Sara Sorribes Tormo in round two after breaking four times and failing to hold only twice against her compatriot.
There was a shock later in the day, as world number 21 Bertens was dumped out 7-5 6-2 by Bethanie Mattek-Sands.
Second seed Sara Errani had no such problems, advancing to the second round at the expense of Cagla Buyukakcay, who went down 6-2 6-3 after failing to hold on six occasions.
Bertens lost to Viktorija Golubic in the Gstaad final on Sunday and Golubic, fresh from her first WTA Tour title, continued her winning momentum with a 7-6 (7-5) 6-1 win over Elizaveta Kulichkova.
Annika Beck, seeded four, responded to her shock defeat to world number 797 Rebeka Masarova in the quarter-finals in Gstaad last week by beating Sorana Cirstea 7-5 7-5.
Lara Arruabarrena could face Wimbledon runner-up Angelique Kerber in the second round after the Spaniard got past Aliaksandra Sasnovich 6-2 4-6 6-1.
Barthel, Laura Siegemund, Lucie Hradecka, Julia Goerges, Katerina Siniakova, Anastasija Sevastova were also winners on day two of the clay-court tournament.