EXCLUSIVE: Reese Witherspoon Gushes Over Lookalike Daughter Ava: 'I'm So Lucky to Be Her Mom'

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Reese Witherspoon is a proud mom!

The Big Little Lies star gushed to ET about her lookalike daughter, Ava, during Elle's Women in Television event in West Hollywood, California, on Saturday.

RELATED: Reese Witherspoon and Nicole Kidman Open Up About the Woes of Motherhood in 'Big Little Lies'

It turns out that 17-year-old Ava has already been mistaken for her Oscar-winning mother.

"I had a premiere for that movie Sing! over Christmas, and the head of the studio went up to Ava and congratulated her on the movie," Witherspoon revealed to ET’s Nischelle Turner. "But I just love her. I'm so lucky to be her mom, and I just love having her in my life and getting to go everywhere with her. It's a great honor."

Mother and daughter look so much alike that it's even hard to tell them apart in a snap shared by the 40-year-old actress on Instagram last week.

"Me and my girl," Witherspoon captioned the sweet pic.

WATCH: Reese Witherspoon Brings Lookalike Kids to 'Sing' Premiere, Talks Singing Katy Perry & Taylor Swift

Witherspoon also dished on Kathryn Newton, who plays her daughter in Big Little Lies and has become her real-life "teenage consultant," when it comes to Ava.

"I'm like, what is this thing on Instagram, and what does it mean with this hashtag?' And she's like, ‘Oh that's this,'" Witherspoon shared before calling Newton "awesome."

Parenting wasn't the only topic on Witherspoon's mind. The mother of three also discussed reteaming with her Wild co-star, Laura Dern, and their quest to get a laugh out of another of their Big Little Lies co-stars, Nicole Kidman.

"We hate each other," Witherspoon said of her and Dern's characters in the limited series, which premieres on HBO on Feb. 19. "It was so fun because she and I love to do comedy, and play, and riff off each other, so I was trying to think of the nastiest things we could say to each other just to make Nicole Kidman laugh."

She may appear buttoned-up, but Witherspoon revealed that she's an apparent pro at getting dirty for the sake of comedy.

"I pretty much topped her by episode two," Witherspoon said of Dern, adding that she got a laugh out of Kidman by being the "dirtiest" that she's ever been.

MORE: Reese Witherspoon Talks Embarrassing Her Kids With Drake Songs at TIFF 2016

On a cleanlier note, Witherspoon, Kidman and their fellow Big Little Lies stars, Zoe Kravitz and Shailene Woodley, cover the February 2017 issue of Elle magazine.

See more on the photo shoot below.