She's best known for playing Sandy in the 1978 movie musical Grease.
But a recent serious health issue has forced Olivia Newton John's management to postpone her American concerts for the rest of May.
Alleged details of her battle with sciatica - a spinal and nerve condition that can render some sufferers unable to move - have surfaced in a report by New Idea.
An insider reportedly told the publication that Olivia's condition has been debilitating.
'So to see her unable to walk or get out of bed because the pain is so severe is incredibly rattling. We are very worried,' the source claimed.
Olivia's management previously announced on her Facebook page that her scheduled performances were cancelled due to health problems.
The post read: 'We are so sorry to announce that the Olivia concerts scheduled for May will be postponed due to a bad issue with Olivia's sciatica.'
'Once the dates are rescheduled we will post the new dates ASAP. Apologies for any inconvenience.'
The source reportedly said the tour cancellation was a big deal for the veteran entertainer, who is known for her professional attitude.
Meanwhile, Olivia is also reportedly concerned for her 31-year-old daughter, Chloe Lattanzi, who has suffered from anorexia and drug addiction in the past.
The insider alleged that Chloe's recent bizarre Instagram posts - which saw her describe herself as a 'Red Bull drinking witch' - have upset her famous mother.
'Just when Olivia thinks she's on the straight and narrow, she starts up with this bizarre business,' they said. 'It's just adding to Olivia's stress and her health troubles.'
In a statement, Olivia said: 'I have had a long running issue with sciatica and I need to take this time to rest and deal with this very painful condition.
'My husband John is taking great care of me and I want to thank all my family, friends and fans for their concern, love, support and good wishes.
'I look forward to returning to performing soon!' she concluded.