In this middle concert of Andris Nelsons’s Brahms cycle with the Philharmonia, it was not just the programme that was dedicated to the music of the German Romantic; both maestro and orchestra showed total commitment to and immersion in the composer’s music – if only in the second half. Before the interval, the Piano Concerto no. 2, featuring soloist Hélène Grimaud, left a little to be desired; but an extraordinary performance of the Symphony no. 4 more than made up for what was wanting in the first half.

Though the performance of the piano concerto was far from unaccomplished, there was a lack of cohesiveness between pianist, conductor and orchestra which resulted in the work seeming somewhat disjointed. It was as if they were in a wrestling match with the concerto’s internal beast, and though they eventually mastered it pacifically in a truly serene third movement, and even flirted with it in the finale, there was a definite sense in the opening two movements that the musicians were clutching at it with their fingertips. This has lots to do with Brahms’ writing: the soloist’s part is monumental in its density and the orchestra shares out its accompaniment in a fragmentary fashion, relying on absolute cooperation and understanding between conductor and pianist, which was never wholly evident.

Grimaud had her hands full – literally – with Brahms’ writing for the instrument, which characteristically favours a packed lower register, and there was a resultant lack of definition in some of the more rapid sections: the rising appoggiatura flourishes which preface the reiteration of the first movement’s grandiose dotted-rythmed theme, or the assertive alternating semiquaver upbeat to the powerful second movement, for example. Towards the end of this movement, however, Grimaud exerted a far greater control over the articulation, as she brought out the cross-beat accents of the piano’s rush to the final cadence brilliantly.

This accentual mastery heralded a far more convincing final two movements, in which Brahms allows a more sensitive approach compared with the staunchness of the opening pair. Timothy Walden’s lyrical cello solo at the start of the Andante incited an air of luxurious relaxation which dissipated the tensions hitherto apparent between conductor, soloist, and orchestra. The most magical moment was achieved in the obscurity of low, held, pianissimo chords in the winds with deliciously slow, rising spread arpeggios in the piano. The suspended weightlessness of this dusky texture, soon caught up in the lilting, loving arms of the cello’s lullaby, was truly exquisite. And as if this contemplative stillness had transformed the work’s angst to airiness, the charming, cheeky fourth movement fizzed along easily; Grimaud sailed through the more mammoth moments with a calmness absent earlier, helped on her way by breezy strings and darting winds, and rocketing away in the coda spectacularly.

The slight tentativeness on the part of the orchestra in the concerto recurred in the famous opening to the Fourth Symphony. Here, however, this was Nelsons’ intention, and after dipping their toes in the opening pairs of thirds, the whole orchestra plunged so deeply into the music that, by the work’s end, everyone needed a few deep breaths. As the tension of those opening fragments reaches ever further outwards across the opening Allegro, the Philharmonia showed its true colours as an ensemble; supremely together, whether in sharp staccato stabs, the lilting compound time rendition of the opening theme, or its paring down to the barest bones before broadening to occupy an expanse intimated previously in amazingly atmospheric pianissimo swirlings, the musicians showed a profound connectedness with both the music and one another to transform the entire concert.

The immense, if often only latent, power of the opening movement was present in the elusive second movement, too, with another musically introverted opening phrase in the horns and bassoons forming the motivic backbone, and a further fantastic foreboding texture of softly scurrying strings over sustained, low wind chords, joined this time by ominous timpani rolls. The joyous opening of the Scherzo soon became playful and lilting, and there was plenty of visual interest on hand too, as the triangle player Peter Fry ting-tinged away at his only notes of the night, and Nelsons performed acrobatic conducting antics such as pretending to dig a hole in time to the music. It was tremendous.

Sombre, serious Brahms returned in the finale, with the densely textured orchestra subsiding under descending semitone scales in the upper winds, and a relentless alternating note, rest, note, rest accompaniment underpinning Katherine Bryan’s vulnerable-sounding flute solo. Momentum builds as the music heads towards an incredible climax, where the orchestra responds again and again, rising in tone and urgency, to violent timpani strikes. In this all the power underlying the entire work – and its performance – was realised, articulated and unleashed, and, after dissipating for a moment, the music was propelled forward to a cataclysmic conclusion.