EXCLUSIVE: Britney Spears Gets Serenaded by 'NSYNC in Unauthorized Lifetime Movie

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Lifetime's unauthorized Britney Spears biopic debuts this Saturday, and ET has exclusive new scenes from the upcoming TV movie!

In an early look at the film, we see Australian actress Natasha Bassett in full Britney mode for a scene in which the pop star is surprised on her birthday with a serenade from the boys of 'NSYNC.

WATCH: Why Natasha Bassett Thinks Britney Spears Will Enjoy Lifetime's Unauthorized Biopic About Her

"You're one year older, girl," Justin Timberlake (played by Nathan Keyes) says in the clip.

The upcoming two-hour film, called Britney Ever After, will span Spears' early days in Kentwood, Louisiana, her high-profile romance with Timberlake and her struggles following her parents' divorce, as well as her short-lived marriages to Jason Alexander and Kevin Federline. It will also cover Spears' custody battle over her young sons and career highlights like kissing Madonna at the 2003 MTV Video Music Awards.


Because the unauthorized project is moving forward without Spears' blessing, Bassett hopes that her hard work results in a performance that wins over the GRAMMY winner. (A rep told ET that Spears would not be contributing to the movie "in any way, shape or form.")

WATCH: Britney Spears Says She Wants to Collaborate With Ex Justin Timberlake: He's 'Very Good'

"I really hope she watches the movie, because I think she'd really enjoy it," Bassett told ET's Leanne Aguilera on the set. "It's really a love letter to her and to her story, so I really hope she watches it and I just wish her all the happiness in the world."

Britney Ever After debuts Saturday on Lifetime.