Diane Keaton Posts About Leonardo DiCaprio's 'Beauty' — But Uses Photo of Reese Witherspoon's Son

MediaPunch/Shutterstock; Jon Kopaloff/Getty; Stefanie Keenan/Getty From left: Diane Keaton, Reese Witherspoon and Deacon Phillippe

Diane Keaton just had a hilarious — but flattering — mix-up, apparently mistaking Reese Witherspoon's son for a famous Hollywood heartthrob.

It all began when Keaton, 75, posted a slideshow video of famous celebrity men to Instagram Monday with the caption "MALE BEAUTY!!!" In a voiceover, Keaton provided commentary for each image, kicking off her collection with a picture of who she thought was Leonardo DiCaprio.

"Talk about beauty, Leonardo DiCaprio," Keaton narrated over a black-and-white image of a young man staring at the camera. "Give me a break. I knew him when he was a kid."

But Witherspoon, 45, chimed in to correct Keaton, writing in the comment section of her post, "Diane, the first one is my son! 😍."

RELATED: Reese Witherspoon's Kids Ava and Deacon Vacation with Their Significant Others: 'I'm So Lucky Man'

While Keaton thought she was posting an image of a young DiCaprio, now 46, the Annie Hall actress was apparently really showing her followers a picture of Deacon Phillippe, Witherspoon's 18-year-old son with ex-husband Ryan Phillippe.

Keaton replied to The Morning Show star with "😳 😳 😳," while Witherspoon simply wrote back, "😂."

While he wasn't intentionally included, Deacon was in good company in the slideshow, which also featured famous faces like Robert Pattinson and Clint Eastwood.

Barry King/WireImage; Stefanie Keenan/Getty

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Witherspoon, who is also mom to daughter Ava, 22 — whom she also shares with Phillippe — and son Tennessee, 9 — whom she shares with husband Jim Toth — often features her kids on social media and isn't shy about sharing how much they mean to her. During a conversation with Gayle King for InStyle magazine's December/January 2022 cover story, Witherspoon called her children her biggest priority.

"My first, most important priority is my kids. If I told you how much space in my brain they take up every day— do you even think they know, Gayle?" she said. "I don't even think they know."

Witherspoon and Phillippe recently celebrated Deacon's 18th birthday and posed together for a photo with their son to mark the occasion. Witherspoon wrote on Instagram, "How did this happen?!! @deaconphillippe is 18?!!"

She added, "One day he was trading Pokémon cards, singing Bruno Mars songs, and playing American Ninja Warrior in the backyard. The next day, he is taller than me, cooking the family steaks on the grill and making his own music with his best friends. My heart is bursting with pride about the young man he is becoming. Happy 18th Birthday Deacon! I love you to the moon around the sun and all the stars ✨ 🥺❤️🎂."