Even when Alyson Hannigan is losing, she's slaying. The Buffy the Vampire Slayer tells ET how much weight -- along with some baggage -- she's lost since joining Dancing With the Stars.

Speaking with ET's Denny Directo on Monday while exclusively on the set with the five remaining couples competing for the Len Goodman Mirrorball Trophy in the season 32 finale, the 49-year-old actress and her partner, Sasha Farber, opened up about their growth while competing together on this journey.

"I think this week, the rehearsals were very different. Yes, it was stressful. It was hard. But there were times where we would be dancing and we would stop and I would just look at her and I would, like, hug her," Farber tells ET. "And I'm like, 'We're here.' We would pause. It was, 'There's no one going home and we've made it.' And she's made it, and she's actually lost 20 pounds!"

"I did," Hannigan responded. "I've lost 20 pounds."

For the actress, losing 20 pounds has also helped her shed baggage she says came as part of some insecurity.

"I think most of the pounds is baggage," she said. "It was all emotions. It was all insecurities. I'm sure 15 pounds of it was insecurities."
 

And now, she's beaming with confidence. The perfect ending, of course, would include winning the mirrorball trophy, which would mark Farber's first.

"I obviously would love that Sasha would get his first trophy," Hannigan says. "And he has worked so hard. I mean, he's had to explain dance terms that, like, he's my Google. He's everything and it would just be so nice to like be able to reward him with something shiny and I like shiny things."

But in Farber's mind, he's already won, which is a testament to the bond he's formed with Hannigan.

"I feel like I've won the mirrorball already to have her, you know. She's lost 20 pounds!" Farber exclaims. "She came in here, and she was shy. She's never danced before. She was unconfident. And now, you know, she stands on her own two feet -- strong, powerful."

He continues, "This show is about the underdog. The true story of someone who's come in, who's never danced before and delivered and came out on top. She's climbed the mountain. It's time for her to enjoy it. And I've been on the show for many seasons. We have dancers and we have couples and we have this, but this is, this is right here the heart of the show. To me. This is what the show is all about."

Hannigan previously spoke to ET and gave credit where credit is due, prompting Farber to refer to Hannigan's body transformation as "Body by Sasha." But the hard work's far from over. Hannigan faces stiff competition for the coveted trophy as she heads into the finals against Xochitl Gomez, Ariana Madix, Jason Mraz and Charity Lawson. 

The Dancing With the Stars season 32 finale airs on ABC and Disney+ on Tuesday 8 p.m. ET. 

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