When performers talk about their work, one often senses a congruence between life and art: this goes as much for instrumentalists as it does for actors, singers or dancers. If you first experience Mitsuko Uchida or Alfred Brendel on record, you won't be surprised by their physical presence: there's truth in the old proverb, le style, c'est l'homme.

But not with French pianist Cecile Ousset. Her celebrated Ravel recordings - delicately expressive, suggesting dark forces under exquisite control - are no preparation at all for the brightly-clad, gaily raucous creature who greets you in the flesh. Only when she tells the story of her life do things fall into place.

She was raised in Algiers, at a time when the city was quintessentially French. She well recalls the first simmerings of revolution, the fear, and her army-officer father's inseparability from his gun. That was in the Forties, but nothing that's happened recently surprises her. "The French left, the new regime became corrupt. And if you stamp out democracy, as the present government did five years ago, what do you expect?"

She was the youngest of six sisters, all of whom studied at the Algiers conservatoire: two pianists, two violinists, a cellist and Cecile. "I began playing the piano at three, before I could read, but there was no merit in my success - the house was full of music." When things got sticky in Algiers, her family decamped to Toulouse, where she went to the conservatoire to immerse herself in Chopin, Schubert and Schumann. "I was a quick learner, but my technique was all over the place. After 18 months, they told my father that my gift required more expert treatment than they could provide, and that I should go to study in Paris. So my father decided we should move there." She says this as if nothing could be more natural than that her needs should dictate the working of the world around her.

"My playing had all kinds of defects, but the professor who listened to me decided I had the sacred flame, and took me on - on one condition: that I should stop playing for six months so that he could deconstruct my technique. He had been schooled in the Russian method of the late 19th century, which was all to do with depth of sound, precision and power, and required great suppleness in the shoulders and arms. I had come to him with fingers bent in the French style, which was at that time a mere obsession with surface brilliance." The treatment worked. At 14, she won the conservatoire's top prize, and went on to triumph in a string of other competitions. With one dip, when she fell into the clutches of a crooked manager, her career trajectory has been smooth ever since.

Her goal, she says, is simply to give pleasure. "And to do that, one has first to please oneself." She hates showy "rediscoveries", such as her compatriot Jean-Yves Thibaudet's unpedalled Debussy. "For me, fidelity to the text is of primordial importance." And she hates the intellectualism of Boulez. "Why play his music? There is no emotion in it. Far better to play Messiaen and Dutilleux." All her reference points are French.

Winning a prize at the inaugural Van Cliburn competition launched her US career: working as a juror for that same competition last year, she damaged her spine so severely that she can no longer play heavy stuff by Beethoven or Tchaikovsky. She had been lugging competitors' dossiers to auditions all round the world: silly, but indicative of the seriousness with which she takes such work. But, in retrospect, she's bracingly indiscreet. Not only did she dislike the playing of one of the Russian finalists, "but I also didn't like his looks - diabolique, a Rasputin".

In the event, Rasputin - aka Yakov Kasman - got the silver; the winner was the San Francisco-Japanese Jon Nakamatsu, whose two-year lap of honour brings him to the South Bank next month. Nakamatsu had played well, but his win was a universal surprise. Was the jury split? "Yes. He was a compromise."

Listening again (on a Harmonia Mundi CD) to his opening-round recital, I have to accept that it may have flashes of splendour, but does him no favours. A non-stop 75 minutes of four such wildly disparate works - by Chopin, Brahms and Stravinsky, plus the competition's unspeakably irritating set-piece - is a tall order in studio conditions; but this was public torture, and you can hear the stress in every phrase. He himself professes unhappiness with this performance.

What was his reaction to winning? "Disbelief. And then, immediately afterwards, a realisation of the responsibility that would now descend on me." While Bay Area newspapers ran ecstatic "local hero" pieces, and language teachers queued up for the day-job he'd finally quit, he was already embarked on the marathon that is the victor's heavy burden. "Two concerts a week for two years: the challenge is keeping fit, getting sleep, and finding time to learn new repertoire." Becoming musically typecast - treated, in effect, as a mechanical toy - is a fate that befalls many competition-winners. Going to pieces entirely - as his predecessor-but-one at the Cliburn did - doesn't look likely with this modest and pragmatic 29-year-old.

I think he will slough off that "compromise" label. There's a nobility in his playing, an impressive refusal of histrionics; he's a proper keyboard poet. In background and lifestyle he may be worlds away from Ousset, but at the piano they're joined at the hip.

Cecile Ousset, 28 Jan; Jon Nakamatsu, 17 Feb. Both at QEH, SBC, London SE1 ( 0171-960 4242)