Margot Robbie and Tom Ackerley are no fans of Blake Lively and Ryan Reynolds, according to an insider who exclusively tells Life & Style it’s quickly turning into Hollywood’s fiercest rivalry by far!

“It’s becoming painfully clear that you can’t be friends with Margot and Tom and also be friends with Ryan and Blake,” the insider says, “and it’s really forcing a lot of A-listers to pick sides.”

Margot, and husband Tom, both 34, spun up their production company, LuckyChap Entertainment, to huge success in recent years, even producing blockbuster hit Barbie, which starred the Aussie actress.

Meanwhile, Ryan, 47, has been hard at work using his own production company, Maximum Effort Productions, to handle the promotion and ad work for his upcoming movie with Hugh Jackman, Deadpool & Wolverine, while managing his many other business ventures, including Aviation American Gin and U.K. football club Wrexham.

Blake, 37, has been hitting the road on her own promo tour, for her movie It Ends With Us, while using the space to market her own line of cosmetics and booze.

“These two couples are the most powerful people in the movie business right now and they all love working with other household names and big celebrities,” the source adds.

Each side in the rivalry is stacking up an impressive list of allies as they meet head to head to see who will seize control of the movie biz.

“Margot and Tom are serious competitors in the Aussie/Brit tradition but frankly, nobody in the business is better at long term career strategy than Ryan – and he’s had Taylor Swift in his corner for more than eight years.”

Taylor, 34, also holds The Proposal star’s wife dear. The country-turned-pop sensation even partied it up with Blake during her end-of-summer party at her Watch Hill, Rhode Island, mansion in August.

“[Blake] celebrated at Taylor Swift’s Rhode Island home which was super special and just what she needed,” a second source previously dished to Life & Style. “She really tried her best to let go of all the drama and have a good time.”

While the “Bad Blood” singer may be securely in Blake and Ryan’s corner, Margot and hubby Tom haven’t exactly been set out to drift by the rest of Hollywood.

Margot Robbie, Tom Ackerley Against Blake Lively, Ryan Reynolds EXCL

The first source continues: “Margot did really win the respect of the smart set in Hollywood with Barbie and picked up a lot of incredible new friends along the way, people who are picky about who they socialize with, like Jessica Chastain.”

“To Margot’s credit, she’s a lot less picky about who she’ll hang out with vs who she snubs, and has made a point to develop multiple projects with Olivia Wilde, even though Olivia is kind of in ‘movie jail’ at the moment after the Don’t Worry Darling debacle.”

“What’s underneath all of this rivalry and posturing?”

“Most people around Margot and Tom believe this all comes from Margot beating out Blake for the star-making female lead role in The Wolf of Wall Street more than ten years ago,” the insider explains.

Martin Scorsese‘s 2012 hit starred Margot alongside the director’s long-time collaborator and A-list box office draw Leonardo DiCaprio.

“They were both TV stars at the time but Blake was by far the more famous of the two of them at the time and Margot’s casting was kind of a shocking coup.”

“After that Margot was a household name.”

“Blake had to marry Ryan Reynolds to become remotely as famous as Margot!”