The actress hired to share the role of Maria in The Sound of Music with talent show winner Connie Fisher has left the Andrew Lloyd Webber production.
Williams has wished Connie Fisher "every success with the role"
Emma Williams, who previously starred in Chitty Chitty Bang Bang, had been contracted to appear in the West End show in two performances a week.
In a statement, however, Lloyd Webber confirmed reports she had "withdrawn her services" from the musical.
Fisher, he said, would perform in all eight shows a week "unless indisposed".
Lloyd Webber drew criticism following reports that an "alternate" Maria has been lined up to share performing duties with the eventual winner of BBC One's How Do You Solve a Problem Like Maria?
The theatre impresario subsequently defended the plan, saying it was "absolutely normal" and necessary to protect Fisher's voice from damage.
In an interview with BBC News 24, 23-year-old Fisher, a former call centre worker from Pembrokeshire, said she "would love to do eight shows a week" if she was allowed to.
Theatre school graduate Fisher will now appear in every performance
Williams, whose other credits include the BBC's Bleak House and the West End musical Bat Boy, is said to have "lots of plans" for the future, according to her agent.
But she declined to comment on reports that the actress had been angered by the decision to reduce her participation in the show from four performances a week to two.
In her joint statement with Lord Lloyd-Webber, Williams said she wished Fisher "every success with the role".
The Sound of Music opens at the London Palladium in November. According to the Daily Mail, more than £6 million of tickets have been sold.