The pop superstar is currently touring the U.S. with her Rebel Heart shows, and the trek has been plagued by reports of delayed start times and rumours she was drunk on stage.

Madonna, who has insisted she would "never drink and perform", hit headlines again after the start of her concert in Atlanta on Wednesday (20Jan16) was delayed by three hours, and the singer issued a statement warning fans they might miss the last train home.

"Due to circumstances beyond our control, the show tonight will start at approximately 10:45 p.m. and will end at approximately 1:15 a.m," the statement issued to fans at the venue read. "Please be aware that the last train will depart... at 1:15 am."

Reports suggest Madonna did not start the show until shortly before 11pm, and during the concert she poked fun at rumours about her drinking by downing a shot of clear liquid and declaring, "Just trying to earn my new reputation as an alcoholic - as I drink shot glasses of water and throw them into the audience... I'm kinda getting used to being misunderstood. It goes with the territory."