Madonna has taken to social media to shoot down rumours she was drunk or high during a Melbourne performance on her Rebel Heart world tour.

The 57-year-old posted to Instagram on Tuesday, sharing the words of a fan who defended her from a “media onslaught” following her Melbourne concert on Saturday night.

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The fan, who identifies himself Remington Graves, argued that Madonna’s “tightly choreographed, intricate, two-hour production” would not be possible if she was intoxicated or under the influence of drugs.

In her own post, Madonna thanked Graves for his support and lamented the “underlying sexism” pervading the music industry.

“I could never do any of my shows high or drunk,” the songstress wrote.

“And yes underlying all of this is sexism and mysongony [sic] which proves that not only do we not get equal pay but we are still treated like heretics if we step out of line and think outside the box!”

The singer, who is currently locked in a custody battle with ex-husband Guy Ritchie for their 15-year-old son Rocco, ended her post on a positive note.

“Sexism is alive and kicking but I am #livingforlove,” she wrote.

Much of the media coverage was sparked by Madonna’s Saturday night concert in Melbourne at which she was seen drinking from a hip flask and making some unusual comments.

“Someone please f**k me. Someone please take care of me, please,” the singer said. “Who is going to take care of me?”

After the concert, longtime friend and industry icon Molly Meldrum told new.com.au the flask was filled with water, a well-known trick of the trade.