'Dancing With the Stars' Preview: What to Expect From 'Eras Night'

— -- "Dancing with the Stars" will showcase the past, the present and the future of dancing on tonight's show.

The seven remaining couples will perform dances from different time periods, ranging from the 1920s to the present as part of "Eras Night."

Riker Lynch will turn back the clock to the '20s for a quickstep with his pro partner, Allison Holker. Their main goal is to impress head judge Len Goodman.

"We gotta show Len that we are hearing him, we're working really hard. And I feel like I've said that every single week, and I'm really trying in rehearsals to give Len what he wants," Holker told ABC News.

Added Lynch: "I want to be the first one that gets the 10 from Len."

"Shark Tank" star Robert Herjavec and his partner, Kym Johnson, are at the bottom of the leader board entering the week -- but they say they're excited about the '80s Argentine tango they have planned.

Johnson said, "Thank goodness we have a slower song, which is really up our alley."

The couple with the highest overall score of the night will be granted immunity and will not be eligible for elimination.

The other couples will compete in a dance-off to tack on extra points to their score.

Sharna Burgess says preparation for the dance-off won't leave much time for her and her celebrity partner, double amputee war vet Noah Galloway, to bicker with one another, as they have in the recent past.

"We can't be worried about arguments on camera," she declared. "This week, it's about dancing for us and we have to make that happen."