NEW YORK -- John Travolta is paying tribute to "Grease" co-star Olivia Newton-John, who died Monday at the age of 73.
In an Instagram post, Travolta wrote, "My dearest Olivia, you made all of our lives so much better. 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 first moment I saw you and forever! Your Danny, your John!"
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, and starred with 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.
Travolta had starred in the stage version of "Grease" and for the planned film thought Newton-John would be the "ultimate" Sandy, the nice girl who gets tough in the final act and gets her man.
"I worried that at 29 I was too old to play a high school girl," Newton-John, who insisted on taking a screen test before accepting the part, told The Telegraph in 2017. "Everything about making the film was fun, but if I had to pick a favorite moment, it was the transformation from what I call Sandy 1 to Sandy 2. I got to play a different character and wear different clothes, and when I put on that tight black outfit to sing 'You're the One That I Want,' I got a very different reaction from the guys on the set."
Grease, released in 1978, was one of the highest-grossing musical movies of all time, earning nearly $400 million at the box office.