'DWTS': Christie Brinkley and Daughter Sailor Get Emotional Over Her Wrist Injury (Exclusive)

The model and her daughter opened up to ET about the last-minute switch-up following her broken arm.

Days before Christie Brinkley was set to take the stage alongside her dance partner, Val Chmerkovskiy, for the season 28 premiere of Dancing With the Stars, the model suffered a catastrophic injury that effectively ended her journey on the show.

However, Christie's daughter, Sailor Brinkley-Cook, stepped up to the plate and took over for her mom with only three days to rehearse their foxtrot. Despite the short notice, Sailor and Val managed to pull off an impressive performance that earned them fourth place on the leaderboard and a lot of optimistic feedback from the judges.

While she couldn't hit the dance floor, the proud mom cheered her daughter on from the audience while rocking her cast. She also joined Sailor and Val backstage after the show to chat with ET's Keltie Knight about the unexpected turn of events.

"I can't even feel this right now, I'm so excited by what just took place," Christie, 65, marveled, holding up her cast-covered wrist.

And it was her mom's perseverance that Sailor, 21, found the motivation and inspiration to take on the DWTS challenge.

"Every moment that I felt like giving up or I felt like I couldn't do it, and it was hours and hours of rehearsal in these past couple days. And I'd just call my mom… and she'd be sitting there in bed with her cast on, and I'm like, 'If she can do that, I can do this.'"

"I'm so lucky," Christie said, getting choked up.

As it turns out, the switch wasn't even as hard as it could have been. Not only did Sailor have to take over her mom's dance lessons, but there wasn't much time to resize the outfits. Luckily for the mother-daughter duo, that wasn't necessary.

"I fit her exact sizes," Sailor explained. "It's pretty wild."

Before the performance, a pre-taped package revealed exactly what happened, and video from the rehearsal showed the exact moment Christie shattered her wrist.

"The second I fell, I grabbed my wrist and it felt like there were sharp things inside of it," Christie recalled. "I knew instantly that I broke it and I knew it was going to be over."

As it turns out, DWTS pro Emma Slater was the first person Christie saw after walking out of the rehearsal studio after breaking her arm, and Emma couldn't believe how composed she was.

"She was holding her wrist and she looked so, well obviously preoccupied, but she was calm!" Emma marveled to ET. "Very calmly she said, 'I think I've broken my wrist. If that's the case, I'm grateful to meet you and I'm so sorry.'"

"She was so lovely! I was like, 'Shouldn't you be in agony right now?'" Emma added. "Because I would be!"

While Christie was calm, the model and actress admitted that she was actually deeply concerned that she was going to let people down by not being able to compete.

"I knew that I was going to disappoint people, and I don't like to disappoint anybody," Christie said, as her voice quivered with emotion while she fought back tears. "I was hoping to inspire women my age, and I hope they don't get the wrong message from this."

"I wanted to make my kids proud, I wanted to make my friends and fans proud, but I felt like I let everybody down," Christie said, as Sailor wrapped her arm around her mom's shoulder in support.

Luckily, Christie's daughter is already showing a lot of potential on the dance floor, and could be a real challenger when it comes to claiming the Mirrorball trophy this season. Check out the video below for more on the Dancing With the Stars season 28 premiere.

DWTS airs Mondays at 8 p.m. ET/PT on ABC.