Watch out! Baby Britney is popping out of the playpen. At a fashion show last Thursday for Kids "R" Us, Jamie Lynn Spears — the pop princess' 11-year-old kid sister — strutted her stuff in cute cheerleader costumes.

But the confident starlet has an agenda of her own — which doesn't include modeling. "I like fashion, but I want to be a singer and actor," Jamie Lynn told The Post

So far, Britney has let her little sister — who has her blond hair and pale complexion — tag along for the ride. Jamie Lynn appeared on stage in "Britney Spears: Live from Las Vegas," starred with Britney in a Pepsi commercial and had a cameo as young Britney in the teen romance flick, Crossroads

But the sixth-grader will soon be stepping out from the sexy megastar's shadow. Nickelodeon has confirmed that Jamie Lynn and her mom have been "in talks" about a project in which the dimunitive dazzler might star — echoes of Britney, who got her big break as a Mouseketeer. 

"We have talked to Jamie Lynn but we don't have any announcements to make at this time," said a spokesperson for the network. 

There's even buzz that  gasp! little sis might be the more talented one. At the show, Jamie Lynn was asked if she thinks she has a better voice than Britney. "Yes, ma'am," she answered modestly. 

Her big sister agrees. "[Jamie Lynn] has a better voice than I do," admitted Britney to the San Diego Union-Tribune last year. "I support her 100 percent." 

Mama Spears also boasts about her baby daughter's pipes. When she sings, says Lynne Spears, "she makes the windows rattle" in their $3 million Louisiana mansion. 

Yet mom says she's not grooming her to be the next Britney. "It's her own thing," she says. "I'm along for the ride." 

Sadly, Hollywood will have to live without the girls' older brother, 25-year-old heartthrob Bryan, who works in product merchandising in Manhattan. Says mom, "He's too macho" for show business. 

We'll hold our breath.

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