In a post to Instagram, the "I Honestly Love You" singer, 72, shared a throwback black-and-white photo of her and Reddy on the tennis court. The two singers wore cute white tennis skirts and held rackets in their hands as they posed arm-in-arm in the vintage shot.
In the caption to the post, Newton-John credited her late friend for helping her find success in the United States. She also thanked the music pioneer for her songs and her passion for female empowerment. Fans know that Reddy's 1972 hit "I Am Woman" became the soundtrack for the women's liberation movement.
In the comments section to the social media post, followers offered Newton-John their condolences as they recalled Reddy's impact on the women's movement.
"Her anthem for women will never be forgotten. #iamwomanherameroar," one fan wrote.
"Helen Reddy was one tough Aussie cookie," another added. "Her determination certainly paved way for success. Now a shining star in the night sky."
"Fabulous photograph remembering such happy times memories there forever," a third wrote.
"I'm so sorry for the loss of your friend. You were both a huge part of my childhood," another user wrote to the singer.Newton-John and Reddy were close friends. They famously performed a duet of the song "I'll Never Fall in Love Again" in a TV appearance in the late 1970s, as seen in a YouTube video here.
But the joint performance might not have ever happened had it not been for Reddy's influence.
On the heels of her own success in the early 1970s, Reddy encouraged Newton-John to emigrate from the U.K. to the U.S. because there were more opportunities in America. Newton-John made the move from England to Los Angeles in 1975, according to a documentary posted on YouTube, seen here.
It was at a party at Reddy's house a few years later that Newton-John met the man who would give her her biggest movie role.
At the party, Reddy introduced her young friend to producer Allan Carr, according to The New York Times. The famous film producer was "knocked out" by Newton‐John's personality and beauty, and he told her she would be "perfect" for his upcoming movie.
That movie turned out to be Grease, opposite John Travolta. Newton-John played leading lady Sandy in the film, which became one of the biggest box office smashes of 1978 and spawned a slew of hits, including "Summer Nights," "You're the One That I Want" and "Hopelessly Devoted to You."