Tonight's episode of "Dancing with the Stars" season 20 will take the contestants and fans onboard a time machine to relive legendary dances and songs from different periods of time. Week 7 of the wildly-popular celebrity dance competition is all about Era's Night. 

This week though, instead of eliminating two couples, the show will only send one pair packing. Also, the couple who gets the highest score will get to enjoy immunity and will automatically move on to the next round of the competition. 

The other six couples will then get the chance to scoop more points with dance-offs. This will be their way to increase their scores and their chances to carry on with their journey in the competition. On the other hand, double elimination will take place on Week 8. 

There are only seven couples vying for the Mirror Ball Trophy, and to get it to within their reach, they will have to pull off an awesome performance and take viewers and the judges to the era they represent with their dances. Here is how it will go down this week: 

• Riker Lynch and Allison Holker— '20s Quickstep

• Chris Soules and Witney Carson— '40s Foxtrot

• Rumer Willis and Val Chmerkovskiy— '60s Jive

• Noah Galloway and Sharna Burgess— '70s Jazz

• Robert Herjavec and Kym Johnson— '80s Argentine Tango

• Nastia Liukin and Derek Hough (or Sasha Farber) — Modern Charleston

• Willow Shields and Mark Ballas — Futuristic Jazz

It is still unknown who Nastia Liukin will dance with this week. Derek Hough, her pro dance partner, has injured his right foot and left ankle so Sasha Farber fills in for him during rehearsals. If Hough does not pull through, he will have to pass this week's dance and have Farber take care of it. 

Meanwhile, singer Andy Grammer will take the stage to sing his very own song titled "Honey I'm Good."

"Dancing with the Stars" season 20 week 7 will air today, April 27. The "DWTS: 10th Anniversary Special," which will gather former contestants for one big dance revelry, is scheduled on April 28.