Mr. Nézet-Séguin, who had been tapped to become music director starting with the 2020-21 season, agreed to start two years early. But his busy schedule as music director of the Philadelphia Orchestra was already fixed. Indeed, even as he leads “Turandot” at the Met, he will be conducting performances with the Philadelphia players at home, and, on Oct. 15, at Carnegie Hall. On Oct. 19 he leads the matinee of “Turandot” at the Met, then dashes to Philadelphia for a concert with the orchestra that night, including Mahler’s demanding Fifth Symphony.

Conducting fine performances and maintaining the excellence of musicians and company members are the most essential parts of being a music director. But it’s just as important to shape long-term artistic priorities. Mr. Nézet-Séguin has talked up some enticing commissions and creative initiatives; we will have to wait and see.

On Thursday, from the scene-setting orchestra burst that begins Act I of “Turandot,” set in Peking in legendary times, Mr. Nézet-Séguin seemed determined to plumb below the brassy, slashing vehemence of the music and reveal its inner secrets. The steady slicing chords that back up the stern proclamation of a mandarin to the people of Peking regarding Turandot’s bloody edict (that all her potential suitors must answer three riddles or pay with their lives) were dispatched with eerie steadiness at a compellingly reined-in tempo.

As the music shifted into passages of velvety richness and tremulous sonorities, Mr. Nézet-Séguin drew out Impressionist colorings and harmonic pungencies . Crucial details in the music, including clashing dissonances that juice the chords, came through with startling clarity.