The first thing Emmanuelle Riva wants me to know – before any mention of movies, careers or awards, before the word “Amour” even enters our conversation – is that she's feeling fine. 

Admittedly, it's not an entirely unprompted statement. She's merely responding to my opening greeting, in which I mention how sorry I was to hear of her recent ill health – words which immediately draw a good-natured but puzzled laugh. “I'm sorry, illness?” she asks over the phone, via a translator, from her home in Paris. “I don't know what you mean.” 

Nervous that I've kicked off an eagerly-awaited interview with an immediate faux pas, I sheepishly explain that her absence at the previous weekend's European Film Awards in Malta – where she was a popular winner of the Best Actress prize – had been explained by the presenter as the result of flu season. Happily, Riva cheerfully confirms, there must have been a misunderstanding. “I'm perfectly fine,” she says. “I was just tired. I've been doing interviews since Cannes!” 

Speaking with bright, alert enthusiasm, making our Canadian translator work hard as she elaborates discursively on ideas with nary a pause, the 85-year-old actress certainly doesn't sound ill – or even tired, for that matter, whatever her claims to the contrary. It's a pleasure to encounter her in such starkly contrasting form to the ravaged, defeated spirit she so hauntingly inhabits in the final stages of Michael Haneke's “Amour.” 

As Anne, a refined music teacher who succumbs with alarming rapidity to the physical and mental recesses of dementia after a crippling stroke, Riva gives one of the year's most remarkable performances: the actorly technique involved in portraying Anne's decline is impressive, but what lingers longest in the memory is the piercing glare of her eyes, persistently protesting the indignities her body is foisting upon her, even when she deteriorates beyond speech. Already laurelled with Best Actress honors from the Los Angeles and Boston critics' groups, in addition to the European Film Award, Riva is now on course to become the oldest lead acting nominee in Oscar history. 

It's a belated career peak for the actress who made an auspicious film debut 53 years ago as a nameless, passion-worn actress in Alain Resnais's New Wave standard-bearer “Hiroshima, Mon Amour” – and one she certainly wasn't expecting. “Reading that script was bliss,” she recalls. “It's rare to be offered a script like that at any age, but how often are such roles written for actors over the age of 80, when you assume your time is behind you? It's miraculous.” 

Though she has never opted for retirement – unlike her co-star, Jean-Louis Trintignant, for whom “Amour” is his first film in nearly a decade – it has been a great many years since Riva has been handed a lead role, let alone one of such complexity. Accepting Haneke's offer, she says, was a split-second decision. “The potential for this film was evident straight away on the page,” she says. “The subject it deals with is just extraordinary: so universal, so essential to everyone's experience, and yet seldom portrayed with great depth in film. I had to say yes. It wasn't a choice.” 

Just because she was certain, however, doesn't mean Riva wasn't intimidated by the project. “I can't remember ever having been so nervous about a role in my life,” says the actress, who describes the fears faced by the film's characters, inevitably, as hitting rather close to home. “When you're taking on a story like that, as an actor, you have to be worthy of that subject. It's life, it's bigger than you. You don't want to fail the subject, and you don't want to disappoint your director.” 

Particularly not, one imagines, when that director is Michael Haneke – the sober-minded Austrian auteur whose career may be green compared to Riva's, but whose reputation for austere formalism precedes him. Still, if anyone's less likely to be overwhelmed by Haneke's standing, it's the actress who began her film career with Alain Resnais, and has since worked with such giants of the medium as Jean-Pierre Melville, Georges Franju and Krzyztof Kieslowski. 

Guy Lodge is a South African-born critic and sometime screenwriter. In addition to his work at In Contention, he is a freelance contributor to Variety, Time Out, Empire and The Guardian. He lives well beyond his means in London.