Daniel Barenboim, Royal Festival Hall, London

If Beethoven's 32 piano sonatas are classical music's New Testament, Daniel Barenboim is turning us all into his disciples. Special seating has been installed for those queuing for returns, and the standing ovations are extraordinary: these things usually start with a few groupies, then others gradually haul themselves up, but with Barenboim, the whole hall is on its feet in a trice. And I can't recall a musical series with so many big- and small-screen stars attending night after night. This disarmingly modest man has become a cultural messiah.

Such deification of course reflects more than his pianism: Barenboim's trailblazing efforts to bridge the Arab-Israeli divide with his West-Eastern Divan Orchestra have caught the imagination of the Western world. But his pianism is proving, to those of us who thought we knew the sonatas inside out, nothing less than revelatory.

His fifth recital, comprised, as usual, of works reflecting the whole sweep of Beethoven's creativity, brought the first memory lapse we have so far seen in this intellectual marathon, but the way he handled it was characteristically impressive. It was only a few bars of the slow movement of the Sonata quasi una fantasia in E flat, but it was unnerving: it suddenly became clear that he'd completely lost the thread of Beethoven's modulation. But by maintaining the mood and tempo, he steered himself expertly back on track.

His confidence seemed dented: in the hurtling finale, he twice smudged passages that depended for effect on lickety-split precision, and there were moments in the sonata that followed when he again fudged crucial notes. But if these were instances of his musicianship running ahead of his pianism, all was restored in the concert's second half, which consisted of the Waldstein and that isolated stylistic landmark, Opus 90.

Barenboim pulled no tricks with the latter, letting the ringing transparency of the first movement speak for itself, and only once breaking the even, conversational surface of the second with a suddenly emphatic gesture. His Waldstein was miraculous: like a conjuror, he brought the graceful theme of the slow movement out of a heavily pedalled mist, and took it back there at intervals. His immaculately prestissimo finale took the breath away. Unforgettable.