The 34-year-old actress proved that she remembers at least one routine from her cheerleading days during an appearance on The Late Late Show on Monday night.
"I loved cheerleading. I was not the most physically adept cheerleader, but I was very vocal," Moore revealed after host James Corden pulled out a throwback photo of her in uniform. "I was passionate and I was loud."
Moore eventually had to put cheerleading on the back burner to focus on singing, because she was "just going to blow out" her vocal cords. That being said, she didn't forget everything she learned.
When Corden asked her if she remembered any of her old cheers, the This Is Us star stood up to perform for the Late Late Show studio audience as well as fellow guest Jenna Dewan. Jumping to her feet, Moore excitedly completed a short chant featuring the low-v motion, along with hopping, spinning and spirited yelling.
"I'm mortified! I just popped my shirt open," an embarrassed Moore laughed after completing the cheer.
When Moore isn't reliving her glory days, she's playing Rebecca Pearson on This Is Us, and ET caught up with her earlier this month to talk about the third season, which premieres Sept. 25 on NBC.
"I have to say... I feel like it's our best season yet," Moore told ET's Keltie Knight. "...It's such a fun time because it's been on the record that our story lines, for Jack and Rebecca at least, one of them is that we're really exploring heavily this season [the time period] when they first meet. And it's so much more fun to be happy and in '70s hair and makeup."
Here's more on what to expect from the upcoming season of This Is Us: