There's only one composer on the menu for most orchestras this weekend, but at least the Philharmonia made sure its celebration of Mozart's 250th birthday would have an individual streak by engaging Mikhail Pletnev as both conductor and piano soloist.

Pletnev's malleable, sometimes indulgent approach to Mozart's orchestral writing could be seen as an antidote to the clean, rhythmically driven style the period-instrument movement has propagated. At the piano, he's something of a loose cannon. In the K382 Rondo, originally written as an alternative finale for one of his earliest piano concertos, the orchestra's playing of the simple, almost trite theme was answered by a solo entry from Pletnev so pensive and free with its rhythm that he could almost have been playing a different work.

With the D minor Piano Concerto, No 20, this quirk developed into a sometimes infuriating pattern. Faster sections would tick along - though the tempo of the first movement was on the steady side - but in the contrasting, smoother melodies Pletnev would be inclined to slow down to frustrating effect. Even the slightest reining in of tempo could be enough to make the music's sense of motion and poise hit a speed bump. It seemed odd, too, to have the orchestra ranked stage left, facing Pletnev across the platform, so that the violins were directing their sound away from us; but it did make for plenty of eye contact between pianist and leader, and some nice interplay between orchestra and soloist.

With Pletnev now on the podium, the Symphony No 40 benefited from crisp orchestral playing but had, initially at least, the same feeling of thwarted flow; the ends of some phrases in the slow movement were almost as drawn out as his cadenzas in the concerto. Yet the finale brought real exhilaration. Pletnev's Mozart may be perplexing, but it's the product of a genuinely independent musical mind. With 11 months of this anniversary year still to come, that's something we may become increasingly thankful for.

· Repeat performance on Tuesday. Box office: 08703 800400.