Leonardo DiCaprio really didn't want to say this iconic Titanic line

Can't imagine the film without it, tbh

Can you believe that Titanic is 21 years old? Since it hit cinemas back in 1998, we've been obsessed with every last detail - from the costumes, to Rose's impeccable hair, to the never-ending debate about whether Jack would have fit on the floating door (ahem, he would - Kate Winslet even admitted that Rose could have saved him after all).

And we're even more interested in what happened behind the scenes. Did you know that this A-list actor almost played Jack? And that Celine Dion's Titanic song almost didn't make it into the final cut? Can you even imagine the film without Leonardo DiCaprio and My Heart Will Go On?

Well, there's another iconic piece of the Titanic puzzle that almost didn't happen.

Think of some of your fave quotes - the most memorable moments of the entire film. Does 'I'm the king of the world!' bubble up in your memory? Of course it does. Jack and Fabrizio enjoying happier times. Sob.

But Leo was apparently reluctant to say it, according to director James Cameron.

Speaking on BBC Radio 1, James said: 'The point is, it [the line] was made up on the spot. Made up on the spot and I was in a crane basket.

'And we were losing the light, and we had tried this and tried that, and we'd tried this line and that line, and nothing was really working.

'And I was literally coming up snake eyes, and I was like, "I've got one for you, just say I'm the king of the world. And just spread your arms out wide and just be in the moment, and just love it and celebrate the moment."

'And he [Leo] goes, "What?!" I'm getting this over the walkie talkie. Just say, "I'm the king of the world, and you have to sell it."'

When Leo questioned James once again, he was told to 'just f**king sell it!'.

And sell it he did, as it's now one of the film's most famous moments.

Next they'll be telling us that 'draw me like one of your French girls' almost didn't happen.