At Tanglewood, a gentleman on Olympus

With BSO assistant conductor Ken-David Masur on the podium, Russian pianist Nikolai Lugansky, one of a stream of young virtuosos pouring out of East Europe these days, passed the flying-fingers, pounding-wrists test with ease Sunday afternoon as soloist in Prokofiev's Piano Concerto No. 3.

LENOX — A big ovation greeted pianist Emanuel Ax when he walked onto the Tanglewood stage Saturday night to play Beethoven's "Emperor" Concerto with the Boston Symphony Orchestra. His gentlemanly ascent of Mount Olympus provoked an even bigger ovation at the end.

Ax is a senior statesman of the keyboard who, to his enduring credit, needs no virtuoso's stunts to show his mastery. His spacious, soft-spoken account of the concerto generated power and pearly runs when needed, but was cast more in a human than the more common heroic mold.

What the cheering passed lightly over was a powerful first half of the program, pairing two distantly related English works. Benjamin Britten's 1941 "Sinfonia da Requiem" mourned a world about to embark on all-encompassing war. Thomas Ad s' 1993 " but all shall be well" evoked mysteries in the world around us. Each work came from early in its composer's career; each was new or virtually new to the BSO.

Previously introduced to the Tanglewood audience as a composer and pianist, Ad s, the BSO's first "artistic partner," made his festival debut as a conductor in this concert. It was doubly auspicious that he conducted his own work and that of a predecessor in the English tradition.

As the title suggests, Britten's 20-minute symphony of requiem is a pacifist's highly personal take on the Roman Catholic Requiem Mass. Britten set only three sections — the Lacrymosa, Dies irae and Requiem aeternam — but did it in a sometimes grinding, groaning manner that anticipates his monumental "War Requiem" from 1962. In the strongly committed performance, Ad s' frenzied Day of Wrath, with its pounding bass drum, recalled Verdi's fire and brimstone in the comparable section of his Requiem.

Ad s, on the other hand, obtains a kind of timeless ambiguity in his " but all shall be well." (The fragment is from a poem by T.S. Eliot.) Gentle chiming and rattles in the percussion open and close the 10-minute piece. Within come ethereal slitherings in the strings, echoed in the brasses.

Will all be well, as the title suggests? Or does trouble lie behind the tonal shimmer? Are the stars shining in those twinkling sounds? Or are clouds dimming night skies in the darker moments? The strength of the piece is in such questions rather than any here-and-now answers.

Ad s, whose "Three Studies from Couperin" had struck beauty amid quiet in an earlier BSO performance, was a strong advocate for his own and Britten's pieces. The accompaniment to Ax in the concerto was attentive but seemed a little too reined-in as it sought to accommodate the soloist.

At an opposite pole from Ax, Russian pianist Nikolai Lugansky, one of a stream of young virtuosos pouring out of East Europe these days, passed the flying-fingers, pounding-wrists test with ease Sunday afternoon as soloist in Prokofiev's Piano Concerto No. 3. Much of the music went by in a blur, but that's probably inevitable with so many barrels of notes being flung about in an open space like the Shed.

This once-shocking 1921 work switches between steel and silk in its clangorous modernity, yet neither quality seemed to get its full due despite the pianist's Russian credentials. The silken melodies, for example, are tinged with irony, as if to say, "Now, don't get sentimental, folks," Here, they seemed just melodies.

We'll have to see what can this gifted pianist do in, let's say, Mozart and Beethoven. Meanwhile, he played Rachmaninoff's Prelude, Op. 32, No. 12, as an encore.                                                                                

In the concerto and two nonstandard orchestral works, BSO assistant conductor Ken-David Masur took charge on the podium. Literally. With gestures that were both commanding and expressive, he had a reduced BSO playing with taut ensemble and vivid excitement. He has matured considerably since his appointment in 2014.                                                                                                                                                           

As the afternoon's opener, Aaron Jay Kernis' 1992 "Musica Celestis," for string orchestra, made good on is title's promise of angelic airs. The hovering medieval mode suggested Vaughan Williams' Tallis fantasia.

Tchaikovsky's Symphony No. 2, the finale, is not great Tchaikovsky but it received a performance worthy of his best. Dramatic and lyrical flair abounded. The finale was a gallop across the steppes. The relatively unfamiliar work, lit by Russian folk tunes, provided contrast to the well-worn Fourth Symphony, performed on Friday night.