Olivia Newton-John, at 65, Doesn't Miss a Beat in Vegas Show

Olivia Newton-John launched her "Grease" inspired "Summer Nights" show in Las Vegas last week with fans, friends and several celebrities in the audience watching the 65-year-old English-born Australian singer and actress perform her classic songs from the 1978 hit film.

"Every vocal was fantastic, and I sang along to every one of them," Marie Osmond told the Las Vegas Sun following the performance. "I haven’t seen her movie 'Grease' 100 times like some in the audience claimed, but definitely a few times. I know all the words to 'Summer Nights.'"

The limited singing engagement was being performed at the Donny and Marie Showroom at The Flamingo, where Newton-John will perform five shows per week until early May, the Daily Mail reported.

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"I wanted her to feel very welcomed to our showroom. She was absolutely great — a pitch-perfect performance," Osmond added.

Olivia Newton-John & Marie Osmond had a great time at the Opening of "Summer Nights" at Flamingo Las Vegas! pic.twitter.com/WuGs1NVFxq

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Other celebrities in attendance at the opening night performance were Joey Lawrence, RuPaul, and Dot Jones.

On person who was not at the show was Newton-John's former "Grease" co-star John Travolta, though the "Summer Nights" headliner told Fox News before the show that she'd "be up for [a reunion with Travolta] if he turns up."

According to Newton-John, Travolta had sent her a personal congratulatory message for the show, Fox News noted.

"For me it's about the music. If it's a great song then it's going to sell itself anyway," Newton-John told Fox News. "People are here to have fun and they're from all different walks of life and different countries and it's always a different experience."

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The Las Vegas announcement is good news after a difficult 2013 for the Australian singer, who lost her older sister, Rona Newton-John, to brain cancer last May, at the age of 70.

"I will miss her forever — my beautiful, smart, talented, funny, brave sister Rona," the 65-year-old actress said at the time.

A breast cancer survivor herself, Newton-John’s support for her sister had led to her postponing a prior Las Vegas show that had been scheduled for April of last year.