Ingrid Fliter/Temirzhan Yerzhanov, Wigmore Hall, London

Live lunchtime broadcasts from the Wigmore Hall have a pleasant fizz. And with the brilliant young Buenos Aires pianist Ingrid Fliter, whose debut disc took the musical world by storm last year, we seemed in for a treat. Launching into Chopin's Grande Valse Brillante Op 18, she delivered its twists and turns with bewitchingly evanescent charm. Reaching the showy conclusion, however, she faltered, banged a note, got up and looked into the piano's works, shrugged apologetically, and walked out.

Were we still on air? What were the listeners in the shires hearing? There was no sign of Radio 3's Fiona Talkington. Instead, on marched the house manager, plus an assistant with a face like an undertaker, who shut the piano's lid. Then they took up the floor, and descended into the depths: three new piano legs appeared, followed by three new pedals, then the sleeping beast was unwrapped and cranked into the daylight. This scene was so surreal that people began to take pictures, until an usher forbade it: 15 minutes later, business resumed.

The remainder of Fliter's recital consisted of Schumann's Etudes Symphoniques, a majestic work requiring a massive feat of imaginative control, but one sensed that she had been knocked off balance. She had clearly thought deeply about how to negotiate the peaks and chasms of Schumann's visionary landscape, and gave it wonderful sweep and grandeur, but some of the variations needed more shape. The theme should have stood out more starkly against the swirl that followed, and there were times when the musical line got lost in a welter of lovingly dwelt-on detail. Her unusual envoi was a pair of posthumous variations which came to us like ghostly, beautiful echoes; her defiant encore was Chopin's Minute Waltz, which in her hands became 90 seconds of show-stopping fun.

When two young pianists tackle major works by Schumann in the same hall on successive days, comparisons are mandatory. The Kazakh pianist Temirzhan Yerzhanov gave us eight pieces from Schumann's Bunte Blatter, plus his Piano Sonata No 1, followed by Prokofiev's Visions Fugitives and Piano Sonata No 2. But in his hands both composers came across as unrelievedly dark and declamatory; the encore was a Chopin nocturne, and even that was ponderous. I note that Yerzhanov records for a label called Con Brio; perhaps he should sign up with one called "Dolce", because at present half his palette is missing.