Jamie Lynn Spears performed a new gig last night -- and one of the songs certainly sounds like it was written about her famous sister, Britney Spears.

The 21-year-old singer hit the stage at 3rd and Lindsley Bar & Grill in Nashville, where she sang a new tune called "I Look Up To You."

"You can imagine who I wrote it about, so I hope you all like it a lot," she told the crowd at the show before launching into the sweet song.

And is it just us ... or does Jamie Lynn look like a mix between classic Britney and Carrie Underwood?

Check out how she's grown through the years in the gallery below:


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