By Caroline Briggs
Entertainment reporter, BBC News
Keira Knightley and Orlando Bloom have let slip that Rolling Stone Keith Richards is definitely to appear in the third Pirates of the Caribbean film.
Bloom and Knightley reprise their roles in the second film
They revealed the rocker would play a cameo role as the father of Captain Jack Sparrow, played by Johnny Depp.
Some observers have drawn comparisons between Depp's performance as the pirate and the 62-year-old guitarist.
Bloom, who admitted he was a fan of the Rolling Stones, said: "I can't wait to see him."
"Well - if he doesn't kill himself falling out of coconut trees. Very rock and roll."
Richards underwent brain surgery in May after reportedly falling out of a tree in Fiji.
Depp is said to have based Captain Jack Sparrow on Richards
It has long been rumoured that the musician was to have a cameo appearance as Depp's father.
Knightley and Bloom, who were speaking at a press conference to promote the second Pirates film, Dead Man's Chest, revealed that Knightley will appear in some scenes with Richards.
Knightley, who appeared at Monday night's premiere in a revealing Gucci dress, also denied newspaper reports that she was suffering from the eating disorder anorexia nervosa.
"I can safely say that I'm not," she said.
"I've got a lot of experience with anorexia - my grandmother and great-grandmother suffered from it, and I had a lot of friends at school who suffered from it, so I know it's not something to be taken lightly and I don't.
"But I don't have it, I am very sure of that."
She added: "It's quite interesting because it's normally high-achieving women who suffer from it because I guess they are control freaks.
"I'm not saying there aren't people in the film industry that suffer from it, because I am sure that there are, but I am not one of them."
Knightley also said she "rejected" any suggestions that she was a role model for young people.
"I think it's completely ridiculous, the idea that you put someone up there and say 'that's how you should behave'," she said.
Depp was nominated for an Oscar for his role as Captain Jack Sparrow
"I make mistakes like everyone else. But having a character as a role model, that's OK - if people look up to a character like Elizabeth in Pirates then that's great."
Dead Man's Chest, the sequel to 2003's Curse of the Black Pearl, also stars Love Actually star Bill Nighy.
He plays the half-squid, half-crab captain of the ghostly Flying Dutchman, Davy Jones, to whom Captain Jack Sparrow owes a blood debt.
Bloom said shooting the scenes with Nighy were among the most difficult as his outlandish costume was all computer generated.
"It was amazing. Everything he did really translated fantastically for that character.
"My hardest scene was when I had to peer through his tentacles, because there weren't any tentacles there. It was an odd thing to have to do."
Bill Nighy's fishy features were added using CGI
While shooting on the third film is still under way, Bloom said filming back-to-back meant it was often hard to keep track of the storyline.
"I would think, oh, I'm in the red shirt, that's means it's three. Your costume gave you the insight into what your character was doing."
Knightley added: "Towards the end of shooting we got really crossed over with three, and I just couldn't remember what was in two and what was in three, therefore I had no idea what the storyline was. It got very confusing.
"So it was great seeing it and saying 'oh, so that's how that works'."
Neither Knightley or Bloom would be drawn on the storyline in the third, as yet untitled, film but producer Jerry Bruckheimer said there was the possibility of a fourth.
He said: "We are hoping to continue the series of films.
"Audiences seem to love it and we love making it, so hopefully we will get the same team back together again to make another one."