Veteran actor Robert Hardy has pulled out of a West End play in which he was to have played Winston Churchill opposite Dame Helen Mirren's The Queen.
Hardy, 87, suffered cracked ribs after a fall and "reluctantly" stood down, producers of The Audience said.
He has been replaced with Bafta-winning actor Edward Fox, the brother of one of the show's producers, Robert Fox.
"That he [Hardy] feels unable to continue is a great sadness to us all," said director Stephen Daldry.
It had previously been announced that understudy David Peart would replace Hardy, who has played Churchill seven times over his career.
Hardy had performed at all of last week's preview performances at London's Gielgud Theatre despite his injury.
"For him to have accepted this challenge at his age speaks of his courage and commitment to the theatre," said Daldry, who wished the highly respected actor and Harry Potter star "a return to full health and strength very soon".
He added: "We are incredibly fortunate that at very short notice Edward Fox has kindly agreed to step in.
"We are particularly lucky to find an actor of such stature and great authority to play Winston Churchill and we are delighted to welcome Edward to the company."
Fox won best supporting actor Baftas for his roles in 1970 film The Go Between and 1978 film A Bridge Too Far, and was nominated for his role in Gandhi.
He also won a TV Bafta for his performance as Edward VIII in Edward and Mrs Simpson in 1979.
The Audience, which has its official opening night on 5 March, sees Dame Helen revisit her Oscar-winning role as Queen Elizabeth II.
Peter Morgan's play depicts the weekly meetings between The Queen and some of the 12 Prime Ministers of her reign, among them Harold Wilson, Margaret Thatcher and John Major.