Lady Gaga has been hospitalised with "severe pain".
The 'Poker Face' singer - who recently revealed she suffers from fibromyalgia, a disorder characterised by muscular pain accompanied by fatigue, sleep, memory and mood issues - has apologised to fans in Brazil after having to pull out of her appearance at Rock In Rio on Friday, September 15.
She wrote on Twitter: "Brazil, I'm devastated that I'm not well enough 2 come to Rock In Rio. I would do anything 4 u but I have to take care of my body right now.
"I ask for your grace and understanding, and promise that I will come back and perform for you soon.
"I was taken to the hospital its not simply hip pain or wear & tear from tour, I'm in severe pain. I'm in good hands w/ the very best doctors (sic)".
She also shared a full statement which read: "Lady Gaga is suffering from severe physical pain that is impacting her ability to perform. As a result, she must sadly withdraw from this Friday's Rock In Rio performance.
"Lady Gaga is under the care of expert medical professionals.
"She sends her love to all her fans in Rio and thanks them for their support and understanding."
Gaga explained earlier this week that the "chronic pain" she is seen trying to tackle in her upcoming documentary 'Gaga: Five Foot Two' relates to the condition.
She tweeted: "In our documentary the #chronicillness #chronicpain I deal w/ is #Fibromyalgia I wish to help raise awareness & connect people who have it. (sic)".
And the 31-year-old singer has been trying unsuccessfully to keep her symptoms at bay.
She posted: "Thought ice helped #Fibromyalgia. I was wrong & making it worse. Warm/Heat is better. Electric Heated Blanket, Infrared Sauna, Epsom Baths. (sic)"