LSO/Petrenko, Barbican, London

The biggest surprise of this concert was just how much the young Russian conductor, Vasily Petrenko, has grown since taking charge of the Royal Liverpool Philharmonic Orchestra. The European City of Culture has scored big with him. But there was an additional surprise in the shape of an added bonus from the UBS Soundscapes: Pioneers series. This laudable experiment gives UK-based composers a chance to write and workshop a short new piece before having it performed by the London Symphony Orchestra as a curtain-raiser to one of their mainstream concerts. Joseph Phibbs' Shruti briefly shone here.

Phibbs, who draws on the Indian connection of his first teacher, Param Vic, sought here to reveal, or unwrap, the music in the playing of it. In a brief interview – though not so brief as the actual piece – he revealed how the process of workshopping Shruti actually prompted him to rethink it, separating the fast music from the slow, meditative core of the composition to form a miniature diptych. So what begins in stuttering, nervy, motion with caterwauling clarinets quickly dissolves into serene stasis wherein a solo clarinet finally unveils a kind of Hindu "blues". Promising.

Petrenko is now well past promising. He and a conspicuously gifted Japanese pianist, Ayako Uehara, really reignited the poetry and pyrotechnics of Rachmaninov's Rhapsody on a Theme of Paganini. This mercurially ingenious piece brought a matching volatility from Uehara. Her range of attacks alone threw the music into the sharpest relief; shifting moods were realigned in a flash. And when she and Petrenko opened the door on the famous 18th variation, the charge in the rubato and sudden surge of enveloping strings really upped the temperature.

That temperature plunged for great swathes of Shostakovich's last Symphony, No 15. Petrenko's command of both the orchestra and the atmosphere in the hall showed tremendous maturity for one so young in a major debut. His patience in this piece was extraordinary as frozen waste gave way to frozen waste – the landscape of Shostakovich's sorrow – and he was blessed by truly meaningful solos from first cello Tim Hugh and trombone Dudley Bright in the elegiac second movement.

But memorable, too, was his way with the parodic elements. In a blistering first movement he really pointed up the rhythmic cell in the horns, which reminds us of the trumpets of Rossini's William Tell, while the irony was not lost on him that the unresolved quote from Wagner's Tristan und Isolde, twice recalled in the finale, saunters off before the famous harmonic ambiguity. Death was always going to be a bit of a practical joke for Shostakovich.