The Circus is turning into a nightmare for pop star Britney Spears, who has reportedly been suffering from persistent panic attacks as she prepares for her upcoming world tour.

According Britain’s The Sun, the Queen of Comebacks has been throwing tantrums and locking herself in her room as she tries to cope with “terrible attacks of nerves.”

“Britney is in danger of not going on tour. She’’s been telling her doctor she’’s under pressure. She fears her performance will be branded a flop.”

The Circus Starring Britney Spears kicks off in New Orleans on March 3.