The element of surprise

If the essence of live music-making is not knowing quite what to expect, then pianist Ivo Pogorelich must rank among the "ultimate" live performers. Tuesday's Royal Festival Hall audience thundered its approval as Pogorelich strolled on stage, reversed his piano stool, then strutted a forceful opening "Promenade" to Mussorgsky's Pictures at an Exhibition.

"The Gnome" harboured a serious power complex but calmed for a meditative central section; then, after a ringing second "Promenade", Pogorelich held the first chord of "The Old Castle" with one hand while simultaneously readjusting his stool with the other. Again, the pulse was free, the rubato interesting if wayward, while the squabble in "Tuileries" revealed exquisite soft playing but quirky phrasing. In "Bydlo" the ox-cart sounded over- burdened almost to the point of collapse; the "Unhatched Chicks" shivered to icy trills; and the "Two Polish Jews" saw Samuel Goldenberg stun poor Schmuyle into a stammering trance.

By now Pogorelich was in full cry: a further "Promenade" led to the madcap mayhem at "Limoges", which in turn tripped straight into "Catacombs", a sombre interlude tailed by a translucent "Con mortuis in lingua mortua" and a violently voiced, if somewhat rickety, "Baba Yaga".

Once past "The Great Gate of Kiev" Pogorelich pushed the pressure but cut some railings. Was it a memory lapse or a premeditated excision? Hard to tell, but the effect was noticeably uncomfortable. Still, this Pictures amounted to a personal, provocative and dazzling pianistic display, more magic than music but not entirely convincing.

After the break, Chopin inspired equal reserves of originality, and rather more insight. Pogorelich lavished maximum affection on the C sharp minor Prelude, an exquisite reading delicately phrased and warmly sustained. But come the First Scherzo and the devil was back, kicking dust with ferocious impetuosity and racing the keys with astonishing ease. Here, too, there was impressive delicacy, albeit not much of a singing line.

A tendency to storm and snatch kept the Second Scherzo nervously hyperactive: the central climax thundered remorselessly, only to be upstaged by the cascading final pages. The Third Scherzo's noble chorale gained in grandeur with each repetition, while the Fourth, although extremely free, was pure thistle-down. All four works witnessed astonishing feats of virtuosity, though - as in Pictures - score-readers will have been flummoxed at every juncture: this was Chopin dressed to kill, as unpredictable, outrageous and outspoken as any since Horowitz's or Cziffra's.

There were encores too, both of them musically substantial: a lovingly distended Schumann Etude symphonique, and then a second thrash at Mussorgsky's "Baba Yaga" and "The Great Gate of Kiev" - better focused, more complete and more accurate than the first. There was a brief standing ovation, but it was useless to shout for more. The sheer exhaustion on Pogorelich's face inspired a respectful if hasty retreat. It had been a wonderful party, but it was definitely over.