Kate Upton May Be an 11 in 'The Other Woman'

You might think bikini acting is all sunshine and white sand, but it's not as easy as it looks, especially those pesky running on the beach shots.

In this exclusive clip from "The Other Woman," experience pays off for savvy swimsuit model veteran Kate Upton.

"She knows how to run in a bathing suit. She said she knows how to do it and not bounce too much,"  co-star Leslie Mann tells Yahoo Movies.

"She's a professional," adds fellow "Other Woman" player Cameron Diaz.

[Related: Nicki Minaj Trades Music for Movies in 'The Other Woman']

In Nick Cassavetes's upcoming comedy, Upton plays Amber, the other woman of the title. Or is it the other other woman?

Yes, it's as confusing as it sounds.

See, Kate (Mann) is married to Mark (Nikolaj Coster-Waldau of "Game of Thrones" fame). Kate catches her man cheating with Carly (Diaz). But then Kate and Carly become unlikely allies when Amber comes along.

In the clip above, we see the moment Kate and Carly realize exactly what they're up against. And things go downhill from there.

"The Other Woman" opens wide on April 25.

See Mann, Diaz, and Upton in the theatrical trailer for "The Other Woman":

Kara Warner contributed to this story.