Margaret Qualley says a combination of intense physical training,alcohol and marijuana helped her navigate the most challenging scene of her career. 

The actress daughter of Four Weddings And A Funeral star Andie MacDowell plays provocative TV aerobics instructor Sue in critically acclaimed film The Substance,alongside co-stars Demi Moore and Dennis Quaid. 

But one pivotal scene involving a highly sexualised dance class led by a lycra-clad Sue,resulted in Qualley 'crying in the bathroom' before she'd even shot her first take. 

'That specific kind of sexuality doesn’t lend itself to me,' the actress,29,told The Sunday Times,admitting she choreographed her routines in private and,when cameras finally rolled,needed a mixture of tequila and weed to push herself through it. 

'I just got wasted first thing in the morning because I was like,I can’t do this in front of everybody,' she added. 

The role required Moore to be naked in a scene where Qualley's character is 'birthed'

Speaking at Cannes Film Festival in May,Moore said the full-frontal nudity scenes in The Substance were easier to perform with Qualley because she made her feel 'very safe'.

'I had someone who was a great partner who I felt very safe with,' she said. 'We obviously were quite close — naked — and we also got a lot of levity in those moments at how absurd those certain situations were.

'But ultimately. it's just about really directing your communication and mutual trust.'

The Substance is released across the United Kingdom and the United States on September 20.  

New York TimesDemi MooreCannes Film Festival