Martha Argerich and Daniel Barenboim were born in Buenos Aires less than 18 months apart and were regarded as the city’s ‘two little wunderkinder’, performing with visiting musicians at the Argentine capital’s musical soirées of 1949. Astonishingly, however, they seem never actually to have played together in the intervening 55 years – until, that is, this much-anticipated Berlin concert, the result not only of lasting friendship and mutual respect but also, one gathers, of some fairly fierce horse-trading.

The opening selection, Mozart’s Sonata for two pianos, demonstrates these two pianists’ contrasting musical characters. Barenboim’s instinct is to sing out, to play to the very back of the hall – although never at the expense of the cantabile that is so essential in all of Mozart’s music. Argerich opted for the second piano part: ‘She is a wonderful accompanist,’ says Barenboim, ‘and I think she wanted to control the pedals and the balance.’ She acts in a way as a moderating influence on Barenboim’s flights, thanks surely in part to her years of experience as a chamber musician. Does it work? After a shaky opening movement (ensemble is often awry and the wonderful hocketing sections from 1'33" passim don’t come off that well), the central slow movement is beautifully shaped and phrased, and the finale, briskly taken, is properly bubbly and joyful.

Schubert’s A flat Variations – like the Mozart, a party-piece of Richter and Britten’s – finds the notes a little more surely under Barenboim’s fingers and builds cumulatively to an intensity comparable with the roughly contemporary Death and the Maiden Quartet, which it resembles in certain motivic and formal ways. The main attraction of the evening, though, was surely The Rite of Spring in the two-piano arrangement Stravinsky made prior to the work’s infamous premiere and which he performed in partnership with none other than Debussy. These two-piano bodges always draw from critics the cliché that one misses the orchestral colouring of the work; and anyway, they are best avoided unless one has a particular interest in the pianists. This shattering performance sweeps away all such notions. ‘I didn’t feel inhibited by the difficulties,’ says Argerich, ‘though it certainly is difficult, rhythmically in particular.’ This is a tour de force of pianistic chutzpah; and if the closing bars of ‘The Adoration of the Earth’ are a little scrambled, that’s Stravinsky’s fault rather than Argerich’s or Barenboim’s. At the work’s close there is a collective gasp from a packed Philharmonie audience before suitably riotous applause breaks out. Your reviewer gasped too.