Summer and Marissa forever! On Monday night, Mischa Barton made her debut on Season 22 of "Dancing with the Stars" with her professional dance partner Artem Chigvintsev. During the first episode of the dance competition show, Rachel Bilson, Barton’s former costar on the hit Fox teen drama "The O.C.," took to her Instagram to give a little shout out to Barton.

Barton and Bilson played the parts of Marissa Cooper and Summer Roberts on "The O.C.," which ran for four season from 2003 to 2007. However, Barton left the show in the third season when her character was killed off.

"Got to give it up for @mischamazing takes balls," Bilson captioned a shot of her television screen featuring Barton and Chigvintsev. "Get it guurrrrlll!"

A photo posted by @rachelbilson on Mar 21, 2016 at 9:48pm PDT

On last night's episode, Barton was enlisted to take on the tango for her first dance, but underwhelmed judges, Len Goodman, Carrie Ann Inaba and Bruno Tonioli. The actress earned a mere 16 out of 30 points for her dance, and a tough review from Goodman almost left her in tears.

"That wasn't a dance," the judge said to Barton. "That was walking! Not enough tango.”

"It's really tough," Barton said when co-host Erin Andrews asked her about how she thought the dance went. "He's a tough teacher, which is a good thing, but it's been a road."

Before the actress took to the ballroom, she blogged about how overwhelmed she had been by rehearsals for the dance competition.

"Like any new working relationship, you never know if your personalities are going to clash or what the teacher-student relationship is to work," Barton wrote. "And I won't lie, in the beginning, things went very slowly and I've had a bit of a rough ride.... Artem would show me a sequence and expect me to pick it up, but all I could do was start laughing because it was so overwhelming."

"The dance is tricky, but I have had a lot of fun helping put it all together," she wrote.

After her first dance, Barton placed in third to last with Geraldo Rivera and Doug Flutie trailing her by a small portion.

"Dancing with the Stars" airs on ABC Mondays at 8 p.m. ET.