NEW YORK  — Olivia Newton-John, the Grammy-winning superstar who reigned on pop, country, adult contemporary and dance charts with such hits as “Physical” and “You’re the One That I Want” and won countless hearts as everyone’s favorite Sandy in the blockbuster film “Grease,” has died. She was 73.

Newton-John, a longtime resident of Australia whose sales topped 100 million records, died Monday at her southern California ranch, John Easterling, her husband, wrote on Instagram.

“Olivia has been a symbol of triumphs and hope for over 30 years sharing her journey with breast cancer,” he wrote. “We ask that everyone please respect the family’s privacy during this very difficult time.”

From 1973-83, Newton-John was among the world’s most popular entertainers. She had 14 top 10 singles just in the U.S., won four Grammys, starred with John Travolta in “Grease” and with Gene Kelly in “Xanadu.” The fast-stepping Travolta-Newton-John duet, “You’re the One That I Want,” was one of the era’s biggest songs and has sold more than 15 million copies.

“My dearest Olivia, you made all of our lives so much better,” Travolta wrote in an online post. “Your impact was incredible. I love you so much. We will see you down the road and we will all be together again. Yours from the moment I saw you and forever! Your Danny, your John!”

“Physical,” the bouncy, R-rated smash released in 1981, was No. 1 for 10 weeks and was named Billboard’s song of the year despite being banned by some radio stations.

“I recorded it and then suddenly thought, ‘Goodness, maybe I’ve gone too far!’” she told Entertainment Weekly in 2017, recalling how the song had been suggested by manager Roger Davies. “I called Roger and said, ‘We’ve got to pull this song!’ He said, ‘It’s too late. It’s already gone to radio and it’s running up the charts.’ I was horrified!”

She is survived by her husband; daughter Chloe Lattanzi; sister Sarah Newton-John; brother Toby Newton-John; and several nieces and nephews.

FILE – John Travolta, left, and Olivia Newton-John arrive at the The Penfolds Icon Gala Dinner in Los Angeles on Jan. 14, 2006. Travolta, who starred with Newton-John in “Grease,” presented Newton-John with the “Lifetime Achievement award. Newton-John, a longtime resident of Australia whose sales topped 100 million albums, died Monday at her southern California ranch, John Easterling, her husband, wrote on Instagram and Facebook. She was 73. (AP Photo/Branimir Kvartuc, File)