Reese Witherspoon Marks Son Tennessee's Fifth Birthday With Sweet Instagram Post
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Reese Witherspoon’s “littlest guy” is not so little anymore!

The Big Little Lies star marked her son, Tennessee’s, fifth birthday on Tuesday by posting a cute photo of the adorable boy on Instagram.

In the pic, little Tennessee posed for his mom by peering through a giant, colorful “5” balloon, which appeared bigger than him!

“Happy Birthday to my littlest guy, Tennessee! ?☀️❤️,” Witherspoon, 41, wrote. “Everyday you bring us so much joy with your sweet smile and beautiful laugh. I love you so much! ? #feeling5 #HBD.”

Tennessee is Witherspoon’s son with her husband of five years, Jim Toth. She also has two children from her previous marriage to Ryan Phillippe, 13-year-old son Deacon and look-alike daughter Ava, who recently turned 18.

Happy birthday, Tennessee!

See Witherspoon tell ET how she embarrasses her kids in the video below.