4:52 PM PT -- Christie is showing support for her daughter, stopping by Sailor's trailer Monday afternoon on the set of 'DWTS.'
As you can see, Christie's got a huge cast over her right wrist, but she looks to be in great spirits despite her injury.
Christie Brinkley's daughter is stepping up to follow in her mom's dancing footsteps ... on the 'DWTS' dance floor.
Sailor Brinkley-Cook -- the 21-year-old model -- will fill in for her mom on the new season of "Dancing with the Stars" ... after she hurt herself rehearsing for Monday night's premiere.
Christie was seen arriving to practice her routine on September 12, shortly before she suffered her injuries. According to ABC, she had to have surgery to her wrist and arm, and will be unable to dance at all this season. Enter Sailor!
ABC released video of Christie going down on 'GMA' -- Christie trips over her dance partner's foot and takes a tumble ... and it looks like she broke a bone bracing her fall.
Couple days later ... Sailor was seen at rehearsals Sunday smiling and preparing with Val. She only has hours to learn her mother's entire routine ... but she, at least, looks ready to crush it as a last-minute substitution.