The very online showdown between and all started with a date: July 21.

It鈥檚 not uncommon for studios to counterprogram films in different genres on a big weekend, but the stark differences between an intense, serious-minded picture about of the atomic bomb and a lighthearted, candy-colored anthropomorphizing of quickly became the stuff of viral fodder.

There鈥檚 even some disagreement over whether it鈥檚 鈥淏arbieheimer鈥� or 鈥淏arbenheimer鈥� or 鈥淏oppenheimer鈥� or yet another tortured portmanteau 鈥� a phenomenon on which the AP Stylebook has yet to offer guidance, but for the purposes of this article will be 鈥淏arbenheimer.鈥�

It didn鈥檛 hurt that both Nolan and Gerwig have very passionate and very online fandoms eager to join in. Never mind that many of those fans overlap 鈥� the memes, allegiances, and T-shirts were just too fun.

Both movies often trend on social media when the other releases a new asset 鈥� a trailer, a picture, an interview. On one level, it鈥檚 a marketing department鈥檚 dream. Awareness could not be higher, the conversation couldn鈥檛 be louder, and neither film even has official reviews out yet.

鈥溾�橞arbenheimer鈥� is a marketing gift borne out of social media and I think it鈥檚 benefiting both films,鈥� said Paul Dergarabedian, the senior media analyst for analytics firm Comscore. 鈥淵ou鈥檙e certainly aware of both movies in a more profound and compelling way than I think might have otherwise happened had they been released on different weekends.鈥�

AMC Theaters reported that 20,000 of its AMC Stubs members had purchased tickets for a double feature. If you鈥檙e counting, that鈥檚 294 minutes of moviewatching. Even 鈥� Barbie herself 鈥� and the star of have started plotting the ideal 鈥淏arbenheimer鈥� day.

鈥淚t鈥檚 a perfect double bill,鈥� said Robbie at her movie鈥檚 London premiere Wednesday. 鈥淚 think actually start your day with 鈥楤arbie,鈥� then go straight into 鈥極ppenheimer鈥� and then a 鈥楤arbie鈥� chaser.鈥�

Cruise 鈥� whose opened a little over a week before the 鈥淏arbenheimer鈥� showdown 鈥� said at his premiere he鈥檇 plan to see both on their opening day, likely starting with 鈥淥ppenheimer,鈥� which seems to be the internet鈥檚 preferred viewing order as well.

鈥淏arbie鈥� actor thinks there鈥檚 a reason for that.

鈥淚 think that there鈥檚 a very specific order that if you see them in. If you see 鈥極ppenheimer鈥� last then you might be a bit of a psychopath,鈥� she diagnosed at the London premiere.

The showdown has made armchair marketing experts out of everyone, quick to scrutinize every move by Warner Bros. and Universal 鈥� as though it鈥檚 possible to compare two extraordinarily different campaigns.

One has infinite opportunities for photo opportunities, whimsical brand partnerships for seemingly everything from underwear to pool floats, large-scale fan events with autograph signings and pop stars like posting about the soundtrack. In other words, the 鈥淏arbie鈥� campaign can go nuclear.

鈥淥ppenheimer鈥� has the bomb, the alluring mystery but it鈥檚 not the kind of movie that lends itself to, say, a frozen yogurt collaboration.

Is the competition real, though, or just a meme? Some in Hollywood wondered if Warner Bros. plopped 鈥淏arbie鈥� on the weekend as a slight to Nolan, who had opened many films for the studio in that corridor including 鈥淚nception鈥� and 鈥淒unkirk.鈥�

He left Warner Bros. amid its controversial decision to send a year鈥檚 worth of movies to streaming and made 鈥淥ppenheimer鈥� with Universal instead. But a pointed box office war doesn鈥檛 exactly make sense for a studio that has talked recently about wanting to lure Nolan back.

There is an unspoken code of conduct: Never badmouth another studio鈥檚 film, publicly at least. This is partly decorum, especially when it comes to 鈥渂ox office showdowns鈥� which all will say are a creation of the press and sideline spectators.

But it鈥檚 also rooted in some truth: The conventional thinking is that having eyes on one movie is good for other movies 鈥� you see their posters and trailers and on some level everyone benefits.

And social media has allowed movie stars to get in on the game, too. Following reports that Cruise was irked the latest 鈥淢ission: Impossible鈥� was going to lose its IMAX screens to 鈥淥ppenheimer鈥� after only a week, Cruise posted photos of himself and standing in front of posters for 鈥淏arbie鈥� and 鈥淥ppenheimer,鈥� holding tickets for each.

鈥淭his summer is full of amazing movies to see in theaters. These are just a few that we can鈥檛 wait to see on the big screen,鈥� Cruise鈥檚 Instagram caption read.

The official accounts for 鈥淚ndiana Jones,鈥� 鈥淏arbie鈥� and 鈥淥ppenheimer鈥� responded with supportive notes. Gerwig and Robbie even followed with a similar photo series a few days later, which the official 鈥淥ppenheimer鈥� Instagram account reposted in its stories.

Charged with playing Oppenheimer, Cillian Murphy told the AP at his movie鈥檚 London premiere that 鈥渙f course鈥� he鈥檇 be seeing 鈥淏arbie.鈥� The sporting cross-promotion between four studios 鈥� Universal, Warner Bros., Disney and Paramount 鈥� is something the film business has not quite seen before.

鈥淣ot only is Tom Cruise the biggest box office star in the world, but he鈥檚 also an incredible ambassador for the movie theater, for the movie theater experience and boosting other movies,鈥� Dergarabedian said. 鈥淎nd that collegial atmosphere within the framework of what is seen as the very competitive box office derby is kind of a nice thing.鈥�

Still, everyone likes a No. 1 debut, and both 鈥淏arbie鈥� and 鈥淥ppenheimer鈥� reportedly carry $100 million production price tags (not including the millions spent on marketing). As far as goes, 鈥淏arbie鈥� has it in the bag with forecasts showing that it could open above $90 million in North America. 鈥淥ppenheimer鈥� meanwhile is tracking in the $40 million range. Then there鈥檚 the wild card of second weekend, which could snag second place.

Still even with a second- or third-place start, 鈥淥ppenheimer鈥� could be destined for a long, steady, profitable run into awards season. Adult audiences for R-rated movies are not often the ones who pack theaters the first weekend.

Back in 2008, in the midst of the recession, Warner Bros. and Universal faced off on the same July weekend with that went up against a lighthearted confection: and 鈥淢amma Mia!鈥� 鈥� both of which went on to be enormously profitable (though Nolan did win the first weekend).

The bigger worry is that what鈥檚 been heralded as has had more ups and downs than anyone might have hoped. That鈥檚 putting quite a bit of pressure on 鈥淏arbenheimer鈥� to overperform and boost the which pales in comparison to the bigger issues facing the industry

But with just over a week to go, it鈥檚 still a source of amusement. Even 鈥淏arbie鈥� co-star threw the gauntlet in his winking way at the London premiere.

鈥淚 think the world maybe wants to see 鈥楤arbie鈥� a little bit more right now,鈥� Ferrell said. 鈥淛ust saying!鈥�

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