The 2001 movie musical starring Nicole Kidman and Ewan McGregor turns 20 on June 1.

To celebrate, we chatted with the man behind the moves.

“We sat around the dinner party and he just had an idea,” O’Connell tells EW.

MOULIN ROUGE!

Everett Collection

“No script, nothing.

But he’s very persuasive.

With each of those numbers comes a selection of explosive, seductive, and electric choreography.

MOULIN ROUGE!

Everett Collection

That’s where O’Connell comes in.

Often the producer will come in and say that, but not Baz.

It’s very freeing.

MOULIN ROUGE!

Everett Collection

If you want to use your imagination.

He’s very supportive of that.”

Knowing he had the freedom to go wild, the first step for the choreographer was research.

“It was crazy stuff, like even pre-Busby Berkeley.

I remember seeing a movie with Ann Sothern and Laurie Chevallier.

It really was like, ‘So what drugs were these people doing?’

But that sort of suited Baz.”

“We had an almost two months rehearsal period, which is quite rare.

No matter how much rehearsal they dancers did, they always had to be adaptable to change.

O’Connell can’t credit the dancers enough for their focus and ability to pick up the choreography quickly.

“I know that I was very lucky,” he says of the dancers he selected.

You really need special people to do a film on that scale.”

He also cites the can-can girls as another example of the dedication the core dancers exhibited.

The dancers weren’t the only ones that impressed O’Connell.

The choreographer was equally wowed by Kidman, who he describes as having an “incredible presence.”

“She doesn’t play safe.

She jumps in and takes the risk.

That bravery led her to do throw lifts in her first number, “Sparkling Diamonds,” too.

“But it was great for the script that they had chemistry.”

“Kylie is a saint,” says O’Connell.

“She spent the entire day in a harness and didn’t complain once.

I absolutely adored her.

She was just heaven.”

“Jim Broadbentwas absolutely and utterly terrified but that’s okay!”

“A lot of the makeup ladies said, ‘We have to go outside.

We can’t watch it,’ because they were all in tears.

They were so overwhelmed by it.

There was something about that.

Sometimes you could do the right steps, you could have the right costume and…

It’s like baking a cake, but the cake just doesn’t cook sometimes.

But with the tango, it cooked.”

They weren’t the only ones moved by the number.

“He said, ‘Oh, you did?