The 26-year-old actress strips down to her bra and underwear in a trailer for Judd Apatow’s Knocked Up spin-off, This Is 40.

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‘Yeah! I’m just young’: Megan Fox tells Leslie Mann’s character in a clip from the new trailer for Judd Apatow’s This Is 40

The film takes ‘A look at the lives of Pete [Paul Rudd] and Debbie [Leslie Mann] a few years after the events of Knocked Up,’ according to the official description on IMDb.

And as the couple tries to cope with the trials of raising a family and getting a little too comfortable in their longterm relationship, the storyline unfolds.

In the most provocative scene, Fox is pictured undressing in front of Mann, a middle-aged mother who seems to long for her youth.

‘Are those real?’ She asks, mouth gaping at the young star’s cleavage.

Sigh: Mann looks longingly at her co-star’s cleavage in the comedic clip

Undressed: Fox, 26, bares her body in a hot pink bra and black and white animal print underwear

A quick frame shows Mann’s character reaching out to poke Fox’s breasts, bulging from a hot pink bra, as her character explains: ‘Yeah! I’m just young.’

The 𝑠e𝑥y comedy role is a departure from how fans have seen Fox in real life as of late.

The actress, who married former 90210 star Brian Austin Green in 2010, is expecting her first child with him.

The actor is already the father of an eight-year-old son, Kassius, whom he had with former wife and 90210 co-star Vanessa Marcil.

Seriously? Mann can’t keep a straight face as the young actress’ shape inspires some envy about her youth

Fox and Green met on the set of TV show Hope and Faith, a show Fox starred in, when she was 18 and he was 30.

Initially engaged in November 2006, the two briefly split in February 2009 after a two-year engagement during which the starlet’s career went into high gear with the first Transformers movie.

Within a few months Fox and Green had reconciled and Green popped the question to Fox for a second time on June 1.

The couple was married in a small ceremony at the Four Seasons Resort on the Big Island of Hawaii on June 24, 2010.

Her new role: Megan Fox and her husband Brian Austin Green, pictured in Los Angeles on June 07, are expecting their first child

Reports of Fox’s pregnancy first surfaced in March this year.

After recently completing filming for This Is 40, the normally booked-up actress now has a clear film slate, with the exception of voice work as Lois Lane on the animated series Robot Chicken.

The Judd Apatow film, also starring Chris O’Dowd, Melissa McCarthy, Lena Dunham, Jason Segal and John Lithgow, is set for release on December 21.