EntertainmentJohn Travolta Praises Olivia Newton-John Amid Cancer Battle: 'I'm Very Proud of Her' (Exclusive)

The celebrated star walked the red carpet at the premiere of his new film, The Fanatic, at the Egyptian Theatre in Hollywood on Thursday, and he stopped to talk with ET where he had nothing but praise for his beloved Grease co-star.

"She looks incredible," Travolta, 65, marveled. "She doesn't look any different than [she did] years ago, and I'm very proud of her."

"I'm very happy about Olivia," the actor added with a smile.

Newton-John, 70, sat down with 60 Minutes Australia, in an emotional interview that aired earlier this month, where she opened up about her latest battle with cancer and explained that she's working hard to enjoy life to the fullest.

Olivia Newton-John Is Determined to Enjoy Her Life as She Battles Stage 4 Cancer

The actress and singer revealed on Sunday that she's living with cancer and doesn't want to know how long she has left in life.

Olivia Newton - John isn’t letting anyone hold her back and has a method for staying positive while battling cancer for the third time – exclusive interview. You have to find the silver lining; there’s good in every bad situation,” the singer says in the latest issue of Us Weekly. “ I ’ m very positive.

Olivia Newton - John opens up to The Australian Women's Weekly about her incredible career, her Read our exclusive full profile below. Olivia Newton - John is in her kitchen – she lives on a ranch "I never call anything my enemy because it's a negative emotion. I ' m just not eating them," she laughs.

ET spoke with Newton-John last week, and the actress shared, "I just want everyone to know, I'm here, I'm doing great. I'm doing really well and I'm really healthy."

Travolta and Newton-John have long been close friends and fans of one another -- but in Travolta's new film, The Fanatic, the actor shows a different, darker side of fandom.

In the movie, Travolta plays a man named Moose who is obsessed with an actor and increasingly begins to encroach on the star's space. The role required something of a radical transformation that included a bizarre, bowl-cut hairstyle and a truly strange overall look.

"I found on the internet this guy that had that haircut and rimless glasses and I superimposed it on a photograph [of me] and I sent it to [director] Fred Durst, and he fell in love with the look," Travolta explained. "Then we added the Hawaiian shirt and the shorts and it just came together, [as] kismet, you know?"

Olivia Newton-John Shares Health Update Amid Stage 4 Breast Cancer Battle (Exclusive)

The 'Grease' star opened up to ET about how she's feeling at the 2019 Industry Dance Awards in Hollywood on Wednesday.

John Travolta has revealed Olivia Newton - John is doing “fine” as she battles breast cancer for the third time. The 64-year-old actor – who “There are other people out there doing much, much worse than me. I ’ m a very privileged person, and I ’ m very aware of that,” she previously told Sunday Night.

John Travolta has revealed Olivia Newton - John is doing “fine” as she battles breast cancer for the third time. The 64-year-old actor – who “There are other people out there doing much, much worse than me. I ’ m a very privileged person, and I ’ m very aware of that,” she previously told Sunday Night.

Travolta said that, when it comes to dedicated fans, he's had some good experiences and he even knows exactly who his biggest fan really is.

"My number one fan in the world is Sharon Travolta," the actor said, referring to a devoted admirer who lives in England and who's been a follower of the actor's work for decades. "She changed her name to my name out of love 40 years ago and on her birthday she watches every movie [of mine] 24/7, and that's kind of her gift to herself and me on her birthday."

The actors' die-hard devotee will soon have another movie to add to her list with The Fanatic, which hits theaters Aug. 30.