The South African song and dance man was thrilled to get the part however, and happy to tackle his second lead role, after performing as Frankie Valli in Jersey Boys for the past few years.
"Playing Frankie was obviously more singing-oriented, so I was ecstatic to get this role because it's a totally different kettle of fish where it's all about your dance stamina. And I've always loved Gene Kelly, I've always loved the romance of all the old MGM stars, the classic movie stars, and I love the aesthetic of this period.
"Between Fred Astaire and Gene Kelly - I've always had an affinity for Gene Kelly, because while Fred was very much the suave, tuxedo-wearing, classy guy, Gene was more of a guy's guy, very charming and dashing. He was certainly a bit of an idol."
The iconic film, which also starred Debbie Reynolds and Donald O'Connor, told a story of Hollywood stars attempting to switch from silent films to talkies in the 1920s. Don Lockwood and Lina Lamont are a Hollywood golden couple - on screen at least.
But Lockwood can't stand his leading lady and in their first film with sound, her voice is grating. Don's musical mate Cosmo suggests overdubbing her with the voice of a chorus girl, Kathy, who Don has taken a shine to.
It was delivered with the comedic sensibilities of the 1950s. That's something Almirall and cast have also worked hard to convey in a stage setting.
"We've been finding with the acting that we wanted to make everything a bit more natural, and lay back into it, but then you realise you can't because it's set in 1927, and people walked differently, and held themselves differently. So it has got a heightened reality to it.
Musical supervisor Robert Scott thinks part of the reason for the show's success is down to the story's place in history.
"The movie came out at the right time; it was produced after World War II when people needed cheering up, Gene Kelly was at top of his game, as was Debbie Reynolds and it's full of iconic moments and fabulous songs. And it's such a fun story that people take it to heart and then, when you put it on stage with real rain, audiences just love it."
Yes, real rain - 12,000 litres of the stuff kept at a comfy 22.5 degrees celsius, requiring half a mile of flexible piping and a 10 tonne water tank. Almirall's Don is saturated to the skin every performance and the production's wardrobe department is kept busy drying his suits.
The show has waterproof mics to keep the company safe from electrocution and those sitting in the front row get rain ponchos with their seats.
The production, now in New Zealand, was cast and rehearsed in Cape Town. The show's cinema sequences were shot there too.
Taryn-Lee Hudson, who plays Lina, says the shoot was a time-consuming production in itself - "Each of the three characters appearing in the filmed sequences has two understudies which meant we needed to do 27 versions of each filmed element that's been one of the most exhausting parts of this whole experience."
So the stage musical which originally started in the 80s now combines video technology as well as spectacular plumbing.
But director Jonathan Church says the show's lasting appeal stems from the original film.
"The original material is bloody brilliant, the most wonderful piece of writing. And the key to the great American musicals is they subtly addressed the horrors of war and the Depression and they took people's spirits and unashamedly lifted them higher.
"Audiences walk out of this show feeling better about themselves and the world. And this particular production is particularly successful because with every step there is freshness, it's something you think you know but because of the way it's been revised - it feels newly minted."
Plus, says Almirall, there's some fine singing and dancing in it, even if he says so himself.
"It's a beautiful show, but the set isn't really particularly lavish, and there aren't lots of special effects, or giant helicopters, or flying robots, so it really does rely on the acting and dancing and the overall performances, which I think always connect with audiences."
It's a story with timeless themes underneath the surface.
"There's the romance, and the big guys versus the little guys, and the tale of what goes on behind the scenes in Hollywood, and I think that's a story that makes sense in any decade."
• Additional reporting Elisabeth Easther.
What: Singin' In The Rain
Where and when: Opening at the Civic Theatre in Auckland on May 1, and runs until May 24
- TimeOut