Director reveals he 'was concerned' about Olivia Newton-John's Grease role

As the world mourns Aussie icon Olivia Newton-John, the man who directed her in her greatest roles has revealed he "was concerned" she wasn't right for the part.

Avid Grease fans know Olivia took some convincing to bring the character of Sandy to the big screen, but director Randal Kleiser told Today Extra he too had reservations she could pull it off.

"She's always been so warm and wonderful to everybody and I always tell everyone that talks about her that she comes across exactly the way she is on film," Kleiser said.

READ MORE: Richard Wilkins breaks down remembering Olivia Newton-John

"That's the way she was - always smiling. I never saw her say anything mean about anyone, I never saw her depressed, she was always just giving love and light to everybody."

Kleiser revealed during filming he had only seen Olivia as the conservative Sandy and had his doubts on whether she could pull off the lycra-clad "bad girl" in the film's finale.

"I knew she could do the conservative character, I wasn't sure about the other one," he said.

"She surprised us all. I think John (Travolta) had total faith in her.

"I was just a little concerned that it might not work at the end but it did, it really did."

READ MORE: Touching way Olivia Newton-John 'handled' superstar's crush

Kleisert, who has considered Olivia as one of his best friends of the past 40 years, said her generosity continued after Grease was released.

"She was so kind to me too, I did a very low-budget movie called It's My Party and Olivia worked for scale," he said.

"She didn't ask for any money, just to help me and be in my personal project."

Watch Randal Kleiser's tribute to Olivia Newton-John above

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