Just like that, it's the semi-finals of "Dancing with the Stars" season 21. The past week has brought surprise eliminations and drama in the show from Alexa PenaVega's emotional goodbye to Tamar Braxton's health concerns, leading to her unexpected exit. Still, today is a new day and the remaining contestants have a tougher road than any other set of semi-finalists.

According to a report from Buddy TV, the original lineup consisted of the pairs preparing two routines each for the night. However, Braxton and partner Val Chmerkovskiy's goodbye meant each couple were assigned an additional performance. For the first time in the show's history, the semi-finalists will be hitting the dance floor for three performances tonight.

With three routines in a single night, those who will make it through will certainly earn their place in the finale.

The first round will have the couples performing their traditional individual routines, a different dance assigned to each couple this week. Frontrunners Bindi Irwin and Derek Hough will showcase their charm in a salsa set to Sia's "You're Never Fully Dressed Without a Smile," while Carlos PenaVega and Witney Carson pay tribute to One Direction with a contemporary dance to "Drag Me Down." Nick Carter and Sharna Burgess will set the tone with a strong tango to "Scars" by Alesso, and real-life hero Alek Skarlatos and pro Lindsay Arnold will be putting on a patriotic waltz to "America the Beautiful" by Ray Chew Live.

The second round will be the fun trio dances, where the couples will be joined by a former contestant pro dancer. Irwin and Hough will dance with recently-eliminated Mark Ballas for a jazz number, PenaVega and Carson will welcome Karina Smirnoff for a samba, Carter and Burgess will collaborate with Peta Murgatroyd for a yet-to-be-confirmed routine while Skarlatos and Arnold will appear onstage with Emma Slater for an Argentine tango.

The extra round will be a dance-off between Irwin and Carter for a samba, and PenaVega and Skarlatos for a cha-cha-cha.

Defending champion Chmerkovskiy lost his chance at a repeat this season with his untimely exit due to his partner's health condition.

"I don't really care about things that aren't important at the moment and at the moment for me the priority was Tamar's health and the situation," he told E! News' Sibley Scoles. "I'm not trying to hear critique on a dance that was done with her half conscious and caused her to be in the emergency room at the moment. For me that's not what is important. I'm just happy that she was alright and she was able to come back and finish out the show. She's a trooper."