Dame Mitsuko Uchida has been associated with Mozart’s piano music for decades. Her superb renditions, based on faithfully reading the score and minimizing the interpreter’s “contributions”, are always eagerly expected. Displaying her typical combination of aristocratic elegance and self-effacing modesty, she conducted from the keyboard two Mozart concertos in the Großer Saal of the Elbphilharmonie. Her equal partners in this latest endeavor were the members of the Mahler Chamber Orchestra, an itinerant group of musicians with different backgrounds but displaying a remarkable sense of common purpose since the days the ensemble was founded under the aegis of the late Claudio Abbado.

Unlike other great instrumentalists active today, Uchida doesn’t claim to be a veritable conductor. Her repertory is extremely limited. She conducts because she has something to say and results are almost always noteworthy. Seen from behind by most of the audience, her arms raised, she had the appearance of a character in a representation of the Passion. You didn’t have to see her eyes to comprehend that leading the orchestra was not just a matter of signalling entries and indicating rhythmical choices but more an extraordinary transfer of energy, thoughts and will from the piano/ podium to the members of the ensemble. Not that the approach to Mozart’s music was always in sync between soloist and orchestra. Uchida had, at times, a tendency to polish her sound until she brings it to the transparency of the 18th century porcelain she is allegedly collecting. Mozart’s music is not necessarily defined by fragility and the balancing act between the more muscular orchestral sound and the piano line was interesting to follow.

The two concertos – no. 17 in G major, K.453 and no. 25 in C major, K.503 – as remarkable as they are, probably don’t make the list of favorite Mozart piano works for most of the listeners. There were exceptional moments: the close, playful interaction between piano and woodwinds in the G major’s Andante; the winds’ abrupt, almost “shrieking” responses in the same concerto’s Allegretto; the way the idiom in K.503’s Allegro maestoso oscillates between the musical styles of two operas – Don Giovanni and Die Zauberflöte – not yet committed to paper. But, if you define a Mozart piano concerto “interest” by its slow movement, these two are more routine, less heart-wrenching than others. Uchida shared with her listeners her keen sense of articulation, her ability to colour shades, the “serious”, crystalline sound with occasional wisps of mischief, all traits that make her playing sound thoroughly individual.

Normally, Mitsuko Uchida’s presence is the focal point of any performance she is involved in. Interestingly so, it didn’t seem that way last Thursday night in Hamburg. In between the Mozart concertos, the 20-year old conductorless MCO offered a hair-raising interpretation of Bartók’s Divertimento for String Orchestra, Sz113. On similar occasions, as when Uchida programmed at Carnegie Hall last year the same two concertos with members of the Cleveland Orchestra, her partners in a recording project, the middle piece offered was a Mozart symphony. Selecting Bartók’s music is not only more challenging from a technical standpoint, but also an illuminating experience. Mozart himself wrote multiple divertimenti along his career but Bartók’s seemingly neo-classical composition is, with its frequent dialogues between small groups of soloists and the ripieno ensemble and the corresponding texture contrasts, closer to a concerto grosso, another 18th-century favorite musical form.

There was an incredible level of energy coming through from each member of the well-coordinated ensemble playing – except the cellos – standing. Every single “voice” was clearly heard, a benefit of the outstanding acoustics of this new hall inaugurated only several weeks ago. Under the fearless leadership of concertmaster Matthew Truscott, the orchestra navigated without fault through the Hungarian folk music inspired syncopated rhythms and through the 14 different metronome markings in the second part. Bartók wrote the Divertimento in a quick two weeks during the summer of 1939, while a guest at the Swiss chalet of his Maecenas, Paul Sacher. He was totally isolated from a world in turmoil and if the Molto adagio slow build towards a striking dissonance was a sign of things to come, as this interpretative version certainly suggested, it must have come from the composer’s wounded psyche.

Most of the audience has obviously attended the performance for Uchida’s Mozart. But the exceptional, challenging experience of the evening came from elsewhere.