IT IS one of the roles of a lifetime and most actors would do anything to have a crack at it: Big Daddy, the cancer-stricken patriarch of Tennessee Williams's Cat on a Hot Tin Roof.
But what if your chance to play the role arrives three days before the first preview performance?
This was the quandary facing Marshall Napier. With Anthony Phelan forced to withdraw from the production through illness in the final straight of director Simon Stone's rehearsal period, Napier was the go-to guy.
''I was at home, relaxing, and the message came through that they had to recast Big Daddy and would I be prepared to jump in, Napier says. ''My first response was: 'You've got to be f---ing joking.' It's pure folly. To try to come up with that character in three nights - even with the script in your hand - is impossible.''
And so he said yes immediately. ''Afterwards, I felt strangely calm about it,'' he says. ''The rational response would be pure panic but I'm not that rational, obviously.''
Besides, says Napier, the gruff New Zealand-born actor who first came to prominence in the early 1990s as ''Frog'' Catteau in the ABC/Southern Star series Police Rescue, there was no time to regret his decision.
''I have moments where I kick myself but I can't really afford to take any of that on board. I'm just focusing on the script, on what I have to do,'' he says.
The rehearsal process is very different for an actor in this situation. There is no opportunity for input, to argue a point or test a hunch.
''I have to accept that,'' Napier says. ''The production is already there. I have to create a Big Daddy who will fit into it. There is some give to a degree, a bit of argy-bargy. If you had to violate all your instincts, it wouldn't be at all convincing. But I've tried as much as possible to go with the pre-existing construct.''
Napier is also aware how disorienting it must be for others in the cast.
''They've all been incredibly welcoming. They're aware of the difficulties and are going out of their way to help. ''It hard on Ewen [Leslie] in particular because he has to work very intensely with me in the second act after everything he's done with Anthony over the past five weeks.''
The opportunity is an exhilarating and frustrating one, admits Napier, who has been performing in previews this week with script in hand.
''It's frustrating as hell, actually. I can see where I can go with the role, but I don't have the freedom to do it yet. And I'm literally rehearsing in front of an audience. I don't have the luxury to feel my way around.''
Cat on a Hot Tin Roof is playing at Belvoir with extra performances at the Theatre Royal until April 21.