An intimate little affair after Beijing but the Royal Albert Hall could not have been fuller. The Lang Lang Olympics were about to commence. A little Sunday-afternoon Mozart – Piano Sonata in B-flat major – eased us into the first lap, articulated with such deftness that the idea of the piano as a percussive instrument seemed almost absurd. The slow movement took on a mystical quality, the dynamics so refined as to lend a whole new meaning to the term "Chinese whispers".
But that's the thing about Lang Lang's playing – you can resist all you like the flamboyant presentation; you can call his playing precious or merely showy; but it's hard not to be seduced by the sheer brilliance and beauty of what he does with the instrument. He followed the Mozart with Rachmaninov's Second and Fifth Preludes, Op 23, and though his pedalling failed to clarify rhythm amid the torrential washes of the former, the arrogant goose-step of the latter was offset with a middle section of rapturous nostalgia, the sound limpid and transparent but charged with a deep regret.
This is what makes his Chopin so special. In the Andante spianata, his fingers seemed to levitate over the keys as if remotely, magically, producing the sound. But behind the cool liquidity of the filigree was an improvisation on sadness – rather like some of those Chinese melodies Lang Lang likes to play to remind us of his heritage. They can be sentimental, but he respects them as he does the Western classics. They mean something to him, and so to us. Lang Lang has a lot of heart – that's what his detractors fail to mention.
But he's a showman, too, and we spent the afternoon in keen anticipation of the Horowitz transcription of Liszt's Hungarian Rhapsody No 2. True to form, the reality was better than the anticipation: witty, audacious, jaw-dropping. So, too, was the arrival of nine-year-old Marc Yu to share the recital's most substantial offering – Schubert's Fantasia in F minor for piano, four hands. This is where things got surreal. Looking like a bespectacled reincarnation of Lang Lang's younger self, this prodigy does not yet have the life experience to know what he is playing, and his presence here smacked of the worst kind of opportunism. But the keys already warmed to his touch and when asked by his idol what this audience meant to him, he pricked the balloon of pretence as only a kid could and replied, in so many words, "not a lot". That'll teach 'em.
BBC Proms to 13 September (0845 401 5040)