Earlier this week, Piper - who is appearing in Treats with boyfriend Laurence Fox - was pictured breaking down in tears and being consoled by ex-husband Chris Evans.
According to producers, however, the play has been delayed to avoid a clash with the RSC production of The Tempest, which stars Patrick Stewart and is also set to open - at the Novello Theatre - on Wednesday.
In an earlier interview, Piper was quoted as saying she was "stressed out" by the impending debut.
"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," she said.