Host Tyra Banks came into the ballroom in full Janet regalia and then introduced her friend via satellite from London. Jackson said she's a fan of all types of dancing, including ballroom.
"I think it's great. I love all styles, all types of dance. It's another way to express yourself," Jackson said. "If you don't do it through words, another way to express yourself is through dance."
The eight remaining couples each performed twice ahead of the semifinals - a solo routine and a head-to-head "dance off."
After their individual dances, three couples earned perfect scores from the judges: Suni Lee and Sasha Farber, Melora Hardin and Artem Chigvintsev and Amanda Kloots and Alan Bersten.
Suni Lee, JoJo Siwa, Melora Hardin and Amanda Kloots each earned two bonus points from various judges after the head-to-head dance off.
Voted as safe: Suni, JoJo, Amanda, Cody and Iman.
In the end, Olivia Jade and Val Chmerkovskiy were the first couple to be eliminated. Then it was up to the judges to decide between Melora Hardin and Jimmie Allen. All of the judges went with Hardin, so it was time to say goodbye to Allen and partner Emma Slater.
Correction: An earlier version of this story had an incorrect title for Janet Jackson's song. It has since been corrected to "Nasty."