Sir Ian McKellen is in “good spirits” after falling off stage during a performance of Player Kings at the Noël Coward theatre in London.
The actor, 85, cried out in pain, calling for help, and a staff member rushed on stage.
Sir Ian had been performing in a fight scene when he seemed to lose his footing.
He was taken to hospital and the play was cancelled.
A theatre spokesman later said that Sir Ian had had a scan and medics said he would “make a speedy and full recovery”.
“Ian is in good spirits,” the spokesman said.
He is expected to be back on stage on Wednesday for a matinee performance of the play.
Player Kings is a production of Shakespeare’s Henry IV, Parts One and Two, and started its 12-week West End run in April.
Sir Ian – who plays John Falstaff – had been circling a battle scene involving the Prince of Wales and Henry Percy when he fell off the front of the stage.
It happened so quickly that at first it appeared to be part of the performance. But the actor cried out and staff rushed to help.
The house lights came up and staff evacuated the theatre.
Tuesday’s performance was cancelled “so that Ian can rest”, the spokesperson said, but added that the actor was expected back on Wednesday.
The spokesperson also thanked two doctors Rachel and Lee who were “on hand in the audience” and staff at the venue for their support.
Paul Critchley, from Downham Market in Norfolk and who was watching the play, said it was a “shock” to see Sir Ian fall off stage “directly in front of the audience”.
Sir Ian’s previous Shakespeare credits include roles as Richard II, Coriolanus, Iago, Richard III, King Lear and Macbeth. He is also set to star as Hamlet, in a new film adaptation directed by Sean Mathias.
His on-screen credits include Gandalf in the Lord of the Rings and Hobbit trilogies, and Magneto in the X-Men movies, as well as roles in Beauty and the Beast, The Da Vinci Code and Mr Holmes.
The actor also appeared in 10 episodes of the ITV soap Coronation Street as the scheming romance author Mel Hutchwright.
Five years ago, Sir Ian was forced to cancel a King Lear showing at London’s Duke of York theatre after sustaining a leg injury while running to catch a train, but ensured the audience was in for a good time, by sitting on stage and answering questions.
Sourse: BBC
