Bindi Irwin's heartwarming birthday message for Olivia Newton-John

She's hopelessly devoted to the icon.

Bindi Irwin took to social media on Saturday, September 30, to wish an Australian icon happy birthday.

Sharing a picture of herself and boyfriend Chandler Powell with Olivia Newton-John, Irwin kept the caption simple but heartfelt. 

“I hope your birthday was beautiful @therealonj,” the 19-year-old wrote. “Love you so much. Your strength and grace inspires the world.”

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The photo of Irwin, Powell, and Newton-John was from the 2016 Wellness Walk and Research Run held in Victoria for the Olivia Newton-John Cancer Wellness & Research Centre.

Read more: Bindi Irwin shares rare footage of dad Steve on Father’s Day

To the uninitiated, it might seem like a slightly odd pairing but the bond between Irwin and Newton-John goes way back. It’s been nearly 10 years since Newton-John sang at a memorial service for Bindi’s father, Steve Irwin, and since then the pair have been photographed at each other’s annual charity events. 

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Newton-John was also pictured cheering on Irwin during her time on Dancing with the Stars, which the young wildlife ambassador won in 2015.

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Earlier this month, Irwin was photographed on the red carpet for the Olivia Newton-John Gala, which aimed to raise money for her cancer charity. 

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Read more: Olivia Newton-John makes 68 look effortlessly cool on red carpet

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The Grease star is currently fighting her second battle against breast cancer. While she won’t talk about the prognosis (and claims to not pay attention to it), Newton-John says she’s feeling positive, and attributes some of her health to the healing powers of medical marijuana. 

“I think we need to change the vision of what marijuana is because it helped me greatly and it helps with pain and inflammation,” the singer said in a recent interview

“I’m doing well, I’m feeling strong, and I’m winning over cancer.” 

Newton-John celebrated her 69th birthday on September 26. 

What do you think of the sweet post?