While rehearsing for Monday night's episode of "Dancing With The Stars," pro dancer Mark Ballas injured his back and ended up having to sit out for the second dance of the season with his partner Paige VanZant.

The 29-year-old dancer has had problems with his back in the past, so he knew the second he felt pain during rehearsals on Sunday night that something wasn't right. During the footage from the rehearsal, which was shown during Monday night's show, Ballas said, "I think I just slipped a disc" and it was very clear he was in pain.

Since Ballas was unable to perform, his UFC fighter partner ended up dancing with pro Alan Bernsten, who stepped in at the last minute and learned the routine in just two hours. Despite the setbacks, VanZant and Bernsten scored a 24 out of 30, which was the highest score of the night. Even though VanZant ended up being safe, it has everyone wondering whether Ballas will be able to return to the dance floor next week.

"The doctor seems to be optimistic, so I'm feeling good about it," he said after the show. "I just don't know how quickly. No time-frame yet...but I don't want to let her down. I want to be there with her, she's fantastic."

He went on to explain how impressed he was with her ability to score so high despite him having to sit this one out. "I'm really proud of her," he said. "I thought she did excellent tonight. It's a hard situation to be put into."

"It was scary. It was very scary," VanZant added. "Allan stepped up and learned the routine very quickly. We had to change a lot of things, which was scary for me. Everything was up in the air...I'm really happy I got to go out there and perform."

Turns out, Ballas had some fancy tricks planned for their Salsa routine and VanZant wasn't positive she wanted to practice them in rehearsal because they hadn't warmed up properly.

"We weren't warmed up, so I wasn't going to do the tricks," she explained. "But he said we had to because we didn't have a lot of time. We'd done the first trick 100 times. But the first time we did Sunday, he hurts his back."

Ballas took to Instagram following the performance to let his partner know just how pleased he was with the way things turned out. "Really proud of @PaigeVanzantUFC she looked so beautiful out there, I was blown away by her infectious energy and her ability to handle this rough situation," he captioned a photo of her and Bernsten. "Also got to say a big thank you to @alanbernsten 'Alaaaan' for stepping up to the plate. I'll be back."

Bernsten also posted two photos of himself with VanZant after their performance with similar thoughtful captions. "Words cannot explain how incredible proud I am of @paighevanzantufc WOW! Thank you so much. Feel better @markballas," he wrote. He then added, "Still in shock with how amazing @paigevanzantufc did tonight! Thank you for sharing this beautiful moment with me."

VanZant posted the same two photos writing, "WE DID IT!!!! @alenbernsten stepped up so I can dance another day. @markballas is healing up!!" she wrote. "Hope we put on a spicy show to get your votes tonight."