When Harry Met Sally is one of the most successful film comedies of all time, not least because of Meg Ryan's famous fake orgasm scene. US actors Alyson Hannigan and Luke Perry face the unenviable task of taking the romantic plot to the stage at London's Theatre Royal.
The pair follow in the footsteps of many US stars, including Nicole Kidman, Madonna and Gillian Anderson, who have come to London to "develop their craft" in the West End.
Alyson Hannigan and Luke Perry will make their West End debut
Hannigan and Perry are both best-known for memorable TV characters.
Hannigan, 29, played lesbian witch Willow in the hit TV series Buffy the Vampire Slayer, while Perry, 38, played bad boy Dylan in Beverly Hills 90210.
This will be Hannigan's first foray into theatre, saying the last time she was on stage was in high school.
Perry joked that for the youthful-looking Hannigan "that was only last week".
Perry, who found fame in 90210, has more experience, appearing on Broadway's Rocky Horror Show.
Both realise they have a challenge on their hands taking on the roles played by Ryan and Billy Crystal.
"I think that after the first few minutes people will see our chemistry and not think about the film," said Hannigan.
Perry added: "I think Billy Crystal would agree, the story is bigger than the actors."
Both decided to do the play because they are fans of the film, which was released in 1989.
'Sign me up'
"I loved the movie. I love the things it says about men and women and relationships," said Perry.
"It's never going away. I truly believe its going to be a classic."
When Harry Met Sally starred Meg Ryan...
Hannigan said: "This was such an amazing opportunity to come to London, which is one of my favourite cities, and I just thought 'sign me up'."
On the delicate subject of recreating Ryan's fake orgasm scene, Hannigan joked she has been practising "all the time".
Musician-of-the-moment Jamie Cullum and his brother Ben are providing the music to the play, reworking music from the movie as well as scoring original songs.
The play is initially taking ticket bookings up to 29 May, but Perry hopes it will be going for at least six months, jokingly pointing out that Phantom of the Opera has been playing in the West End for years and they could follow suit.
But Hannigan may have other ideas, having recently married actor Alexis Denisof who she met on the set of Buffy before he moved to its sister show Angel.
"Being away from him was the biggest drawback to the job," she said.
"I've been offered a few things that would have taken me away from home since we got married and they were easy to turn down.
...and Billy Crystal in the title roles
"But this was too good to say no to."
She added that they have every kind of technology to keep them in touch, and was excited at the prospect of him coming to London next week.
Buffy has now come to an end after seven series, and with such a cult following it is easy to see Hannigan having difficultly shaking off her Willow character.
But she said that starring in the recent movie American Wedding, the third in the American Pie series, and a development deal for a sitcom has meant she has been able to move on quickly.
Perry, still remembered for his 90210 days despite numerous movie roles, said he took some sound advice on how to deal with his TV past from one TV's most famous characters - The Fonz.
Hannigan stepped up the aisle in American Wedding - the third American Pie film
"Henry Winkler gave me some advice, he said 'you created something out of nothing and people are going to remember that for a very long time'," said Perry.
Now both Perry and Hannigan will be hoping they can put their own stamp on two of movie histories much-loved characters, Harry and Sally.
When Harry Met Sally opens at the Theatre Royal Haymarket, London, on 20 February.