Christie Brinkley's daughter Sailor on stunning 'Dancing With the Stars' performance: 'I did it for my mom'

Sailor Brinkley-Cook looked right at home Monday night on "Dancing With the Stars," earning an 18 out of 30 on her first dance, landing her among the early leaders.

Brinkley-Cook joined the season's cast at the last minute to replace her mother, supermodel Christie Brinkley, who had to pull out due to a serious injury.

So, the 21-year-old model had a good reason for prepping so hard and performing so brilliantly in the season premiere -- "I did it for my mom."

"Getting out of the car. Seeing her face. She... made everything worth it, the rush of it all!" she told "GMA."

After the performance, she added that it "was a very emotional moment of course."

"I think everything was moving so quick in these past few days, I haven't even had a second to digest what happened to my mom, what’s happening to me," she said. "I'm just like, now I'm just feeling this immense gratitude, for my mom, for myself, I never thought I could do this."

But before Sailor took off on her journey, Christie shared a moment of "empowerment" the duo had.

"I literally caught her on the runway as her plane was taking off," Brinkley said. "I'm like, 'Sailor, are you gonna let fear dictate to you, no!'"

The news came out Monday that Christie was out after hurting her wrist and arm, which required surgery.

"I wish I was still part of the cast and not wearing one ... It was major surgery they cut it open and put in screws," she explained to "GMA."