World number six Wozniacki, the top seed in Bastad, won 6-2 2-6 6-4 to set up a quarter-final clash against Ukrainian qualifer Kateryna Kozlova, who overcame former champion Mona Barthel 6-3 6-3.
Spain's fifth seed Carla Suarez Navarro bowed out of the tournament after a marathon three-set defeat to Belgium's Elise Mertens, who triumphed 6-3 6-7 (2/7) 7-5 in nearly three hours.
WTA Bastad
Anastasija Sevastova breezes into the second round in Bastad
24/07/2017 AT 21:29
Czech Republic's Barbora Krejcikova is through to the last eight after being handed a walkover against sixth seed Kiki Bertens.
Lu Jingjing reached the quarter-finals of the Jiangxi Open in Nanchang after recovering from a set down to beat Jelena Jankovic 2-6 6-1 6-2.
Jankovic struggled in temperatures reaching 39C and called for a trainer during one changeover when a medical timeout was called before play resumed after a 10-minute delay.
Lu will face Nao Hibino for a place in the semis. Japan's Hibino progressed after third seed Karolina Pliskova was forced to retire due to a hand injury as she trailed 3-0 in the opening set.
Second seed Peng Shuai also went through after her opponent retired, with Tereza Martincova unable to continue with the score at 6-2 3-2 against her.
Peng Shuai now faces Zhu Lin, who went through to the last eight after beating Xun Fangying 6-3 6-4, while Wang Yafan overcame Chang Kai-chen 6-0 6-2.
WTA Washington
Kyrgios sets up Nishioka final at Citi Open, Norrie loses to Medvedev in Los Cabos
Highlights: Kyrgios sees off Ymer in straights to reach Citi Open final