CNN
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James Cameron is sharing some surprising details from the making of his blockbuster hit “Titanic,” which celebrates 25 years of being released next month.

In a new video interview with GQ, the iconic director revealed that he almost didn’t end up casting Leonardo DiCaprio or Kate Winslet – his two romantic leads whose careers as major Hollywood movie stars were cemented by the landmark Oscar-winning film.

While considering actors to play the roles of his star-crossed lovers on the doomed ocean liner, Cameron explained that he was initially thinking of someone like Gwyneth Paltrow for Rose, and that while Winslet had been proposed as an option, he was afraid she was too much of a typecast.

“I actually didn’t see Kate at first,” he said in the video. “She had done a couple of other historical dramas as well, and she was getting a reputation as ‘Corset Kate’ doing historical stuff.” (It is true that “The Reader” actress’s three credits prior to “Titanic” were also period costume dramas – “Sense and Sensibility” in 1995, followed by “Jude” and “Hamlet” one year later.)

Cameron went on to say that he was afraid that putting Winslet in the role “was going to look like the laziest casting in the world,” but that he nonetheless agreed to meet her in the end. Of course, he thought she was “fantastic,” and the rest is history.

With DiCaprio, meanwhile, there were some initial hiccups.

After an initial “hysterical” meeting with the heartthrob actor, in which all the women in the production office somehow ended up in the conference room alongside Cameron, DiCaprio was invited back for a screen test with Winslet, who had already been cast at that point.

But when the “Romeo + Juliet” star came in, he was surprised to learn he’d have to read lines and be filmed alongside Winslet to gauge their chemistry on camera.

“He came in, he thought it was another meeting to meet Kate,” Cameron described.

He remembered telling the pair, “We’ll just run some lines, and I’ll video it.”

But then DiCaprio – who by then had led several movies and scored an Oscar nomination for 1993’s “What’s Eating Gilbert Grape” – informed Cameron, “You mean I’m reading?…I don’t read,” meaning that he no longer submitted to having to audition for film roles.

Without missing a beat, Cameron extended his hand to the star and and told him, “Well, thanks for coming by.”

The director then explained to DiCaprio the enormity of the project before them, how the film was going to take two years out of his life, and how he was “not going to f**k it up by making the wrong decision in casting.”

“So you’re going to read or you’re not going to get the part,” Cameron said he told the young actor.

DiCaprio reluctantly submitted, to his credit.

Cameron remembered how the actor “lit up” and “became Jack,” creating electric chemistry with Winslet later seen plainly in the film itself.

“Titanic” sailed into theaters on December 19, 1997 and eventually went on to win 11 Academy Awards, including best director for Cameron.