Reese Witherspoon reacts after son Deacon is mistaken for Leonardo DiCaprio - the resemblance is uncanny

Reese Witherspoon was forced to step in after Diane Keaton mistook a snap of her son Deacon for Leonardo DiCaprio.

The Morning Show star stumbled across a post in which American actress Diane Keaton uploaded a series of black and white photographs to celebrate beautiful famous men including Jason Momoa, Zayn Malik, Robert Pattinson, and captioned them 'MALE BEAUTY!'

But what she didn't realise is that the first image - that she narrated, "Talk about beauty, Leonardo DiCaprio, give me a break,” she wrote in reference to the first photo.

Hilariously, Diane thought the photo was of iconic Titanic actor Leonardo DiCaprio - but it's actually Reese's 18-year-old son, Deacon.

And the resemblance between young Leo and Deacon is uncanny.

Responding to the post to point out Diane's mistake, Reese penned, "Diane, the first one is my son."

And Diane isn't the only one to be fooled thinking it was a throwback snap of Leonardo DiCaprio, who recently met up with Prince Charles.

Another fan added, "Leonardo DiCaprio 😍😍"

And one more chipped in to say, "I’m watching Titanic right now and Leo is👌🏼(as is Kate🔥)"

But a fourth was unsure, and put, "I do not think that was Leo. I mean it does not look like Leo, @diane_keaton but I love your pics."

Reese has three children, sharing daughter Ava, 22, and Deacon, with ex-husband Ryan Phillippee.

She is also mum to son Tennessee, nine, who she shares with husband Jim Toth.

And Deacon proved he shares his parent's gorgeous genes when he was pictured with his mum and dad on his 18th birthday earlier this year.

Proud dad Ryan captioned the snap, "Happy 18th birthday to our gorgeous, smart, talented, and caring son. You are a true light in this world and are so loved by all who know you. We are lucky to be your mom and dad. Love you, pup..(I’d say we did pretty good @reesewitherspoon)"

Reese previously opened up about postpartum depression and revealed she now finds parenting rewarding.

Reese said, "I never expected the kind of relationship that I have with them, but it’s so rewarding to be able to have kids that you can process life with a little bit, and they help me understand the complexities of what it means to be a human now.”

Reece Witherspoon is currently filming The Morning Show Series 3.