Billie's West End debut is postponed
The play, being put on at London's Garrick Theatre sees Piper star alongside her boyfriend Laurence Fox.
According to the Daily Mail the theatre industry is rife with rumours that the Doctor Who star is finding the role very challenging.
She told the newspaper: "It's really hard in the theatre and the level of concentration is terrible. I am still working it out and trying to find my feet...I am quite stressed and am having a tough time."
But a spokesman for the play denied that the delay had anything to do with Piper's ability, instead saying that it was caused by a clash with the Royal Shakespeare Company's production of The Tempest.
He said: "The reason for the move is that it clashes with the RSC. It is something that has been discussed for a while."