More pictures of Alexa at the Dancing with the Stars rehearsal studios, on September 3rd & 4th.

​Just for fun, here are two predictions on how well Alexa will do on DWTS this season.

From Hollywood Take, September 2nd:

Then there are the wildcards among the DWTS Season 21 cast. It’s hard to predict how married couple Alexa and Carlos PenaVega (paired with Mark Ballas and Witney Carson, respectively) will perform in 2015.

Alexa showed potential in the Dancing promos, but she may not have that strong of a fanbase.

From Buddy TV, September 4th:

Carlos PenaVega and Witney Carson: Carlos is young, good-looking and from Big Time Rush, a band/TV show that required him to do choreography. Fellow BTR member James Maslow made it all of the way to fourth place in season 18 while Witney Carson won with Alfonso Ribeiro and dragged Bachelor Chris Soules to fifth place. If I were them, I'd already be planning my Freestyle.

Alexa PenaVega and Mark Ballas: Alexa, as an attractive actress and singer in her 20s, fits the mold of recently successful stars like Rumer Willis and Janel Parrish (making a bit odd she's not partnered with Val). She has everything you might look for in a winner, plus the added bonus of competing against her husband. After all, being the female half of a duo worked out very well for Meryl Davis.

Before the first dances even take place, I predict that Alexa PenaVega and Mark Ballas will win Dancing with the Stars season 21. She has the right look and build to go far and he's a fan favorite choreographer who proved last season that he can come up with inventive concepts.

One "wild card" and one "she'll win the whole thing." It's going to be very important for us fans to make sure we vote for Alexa every week to keep her in.

​Live in or near L.A.? Come down to the El Capitan Theater at 9pm on September 10th on Hollywood and Highland to be part of the DWTS season premiere flash mob!

The celebrity and pro pairs are revealed in this video. Alexa's partner is Mark Ballas. Carlos will be dancing with Witney Carson.

The @DancingABC cast will be revealed tomorrow LIVE on @GMA!

Tweet questions for the cast with #DancingOnGMA! pic.twitter.com/XflLy2NCFI

— Good Morning America (@GMA) September 1, 2015

Alexa and Carlos PenaVega will be on @DancingABC. Who else will be revealed tomorrow on @GMA? http://t.co/owN2bl6SH3 pic.twitter.com/wwxGEtrzj3

— Good Morning America (@GMA) September 1, 2015

Alexa started rehearsals for Dancing with the Stars this week! We have pictures from outside the studio from the 27th, 28th and 29th.

There are also videos of Alexa and Carlos dancing separately.

Alexa and her husband Carlos will be joining Season 21 of Dancing with the Stars!!!

Married couple Alexa and Carlos PenaVega will compete on season 21 of Dancing With the Stars, ET exclusively and officially reveals.

"It's so exciting," Alexa, who is also celebrating her 27th birthday today, gushed to ET's Cameron Mathison. "It's beautiful, it's overwhelming, it's an incredible blessing."

Alexa and Carlos will be the first-ever married couple to compete on the show. Don't miss the season premiere Monday, Sept. 14 at 8 p.m. ET on ABC. (Source 1 & 2)