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They're a long way from "The O.C.," but Rachel Bilson still has Mischa Barton's back.

Like many others, the actress who played Summer Roberts on the beloved Fox show sat down on March 21 to watch her pal on "Dancing With The Stars."

Mischa, as you'll recall, played Marissa Cooper on the show.

"Got to give it up for @mischamazing takes ba---," Rachel, the mother to 1-year-old Briar Rose, said in a captioned screenshot of her old costar and her pro partner, Artem Chigvintsev, on the TV. "Get it guurrrrlll!"

Although many people were pulling for her, Mischa's performance wasn't received super well by the judges, who gave her the third lowest score of the night, with a 16 out of 30 for her tango dance.

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Mischa had admitted during rehearsals that she was nervous to take the stage.

Judge Len Goodman said that it was like she was walking instead of dancing, which Barton considered to be a "harsh" critique.

Among other digs, Len accused her of walking through her number. "That wasn't a dance," he quipped.

After the premiere, the actress told Entertainment Weekly that was was relieved that it was over, adding that she was frustrated with the performance.

"I was more annoyed with stuff off the top, the actor-y [stuff]," she tells EW. "I don't see all this stuff that they see all the time."

Her professional partner said, "The thing is, when someone comes into a competition like this, it's quite hard to commit in general, and then to come out for the first time and perform live, doing something you've never done before, I feel like there should be more encouragement."

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Before the competition, Mischa told People magazine that she's excited to push her limits and "learn something" about herself on the popular ABC show. She even said she had a previous champion in her corner -- Rumer Willis.

"She told me, 'You are going to have the best time. It's like family,' " Mischa said of Rumer's advice. "And that's exactly what it's been like so far."

… And family tells the truth, right Len Goodman?