Putting the best-ever foot forward at season-opening concerts at Carnegie Hall and the Kimmel Center means something less classical than usual for the Philadelphia Orchestra on Wednesday and Thursday. A semi-pops Gershwin/Bernstein repertoire replaces the Tchaikovsky, Ravel, and other composers who would typically show off the famous Philadelphia sound.

In such visible circumstances, is this what Yannick Nézet-Séguin & Co. do best?

Maybe yes, but explaining why Nézet-Séguin has nailed these ultra-American composers in recent seasons doesn’t come easily. “Gershwin? I have no idea,” he says, back at work after being sidelined this month by tendinitis. “It probably always remains mysterious why musicians have affinities with one thing more than another one.”

Both concert programs draw on what he did not grow up with in French-Canadian Montreal: Hollywood, Broadway, and Tin Pan Alley. Wednesday at Carnegie Hall has Bernstein's suite to the film score of On the Waterfront, Symphonic Dances From "West Side Story," and Gershwin's Rhapsody in Blue with pianists Lang Lang and Chick Corea. The opening slot for the Carnegie season reaffirms the Philadelphia Orchestra's New York presence dating back to 1904.

On Thursday at the Kimmel, a similar program without Lang Lang features pianist Harmony Zhu, age 11, winner of the Albert M. Greenfield Student Competition and now a Juilliard School student. She plays part of Beethoven's Piano Concerto No. 1.

Immediately after that at the Kimmel (Oct. 6, 7, and 8), the orchestra will be more in its element with Emanuel Ax playing Mozart's Piano Concerto No. 27 and a new work by Wayne Oquin titled Resilience with organist Paul Jacobs. But walking on the light side during certain parts of the season is happening with the best of them. Not so long ago, the New York Philharmonic played live accompaniment to the film Babe (the one about the pig).

"I think the Philadelphia Orchestra has embraced a broader definition of our repertoire — as well as the industry as a whole," said Jeremy Rothman, vice president of artistic planning. "These are fantastic scores that deserve full hearing."

Obviously, the 100th year of Leonard Bernstein — who graduated from the Curtis Institute and tried out Broadway shows in Philadelphia — is one motivation behind the program, and Bernstein had strong roots in Gershwin. Rothman also points out that more serious Bernstein symphonies, such as his Symphony No. 3 ("Kaddish"), which contemplates the nature of religious beliefs, aren't rousing season openers.

Though lighter-weight concerts can look like a walk in the park for the orchestra, they have hidden challenges. Older musicians recall a time when Gershwin's An American in Paris required an outside trumpeter to be hired for the bluesy solo in the middle of the piece.

Bernstein's vernacular-tinged concert works can sound starchy when not played by U.S. orchestras — or at least ones not led by the composer himself. Some of the worst Gershwin recordings came out of Europe in decades past. Now, some of the most alert performances of both composers come out of England and France.

Or French Canada.

Even before Nézet-Séguin‘s Philadelphia appointment, radio broadcasts from Montreal had him conducting Gershwin’s Concerto in F in ways that put his American counterparts in the shade. Bernstein’s On the Waterfront score has the extra challenge of unfamiliarity outside the film for which it was written. Nézet-Séguin hears it as a true concert work and calls it a masterpiece of its kind — though in-depth understanding of it is maybe not so dependent on studying the Marlon Brando film, he said.

"When conducting Mendelssohn's Scotch Symphony, do I attach great importance to pictures of the Scottish coastline? " he said. "The film helps you know the environment, and how New York was a little rough and raw in that period. But the poetry has to be between the notes and not about the imagery. … At some point the music has to be taken for pure music."

Composer/performer affinities are often explained by conditioning. Nézet-Séguin‘s Bruckner specialty may come from the two having been steeped in Catholicism. “As a child, I wanted not only to be a priest but the pope,” he acknowledges.

With Gershwin, Nézet-Séguin has only one thing to go on: rhythm. “To me, the key is the rhythmic vitality. In anything I conduct, I always try to keep the pulse, the basic dance pattern. …Whenever I conduct any American music, I try to get back to the rhythmic center.”

Somehow, the result of that has included a Nézet-Séguin performance of Bernstein’s Symphony No. 1 (“Jeremiah”) last season that made new converts to that piece. Older critics of Bernstein’s 1971 Mass may still hear the music as synthetic flower power. But in his 2015 performances of the piece, Nézet-Séguin perceived a brilliant collage of genres. “I’m sure that the perspective of a later generation is probably helpful in that,” he said.

For all West Side Story’s familiarity, its complete Philadelphia Orchestra performances Oct. 12 to 15  may have the most challenging transition to the concert stage. This is not an accompaniment to the film — as in past seasons — and will have singers but no dancers. “The exercise here is to try to revisit the music for what it is,” said Nézet-Séguin. “So, the presentation won’t be static and we won’t have music stands onstage. But there won’t be choreography.”

The music pushed the limits of the Broadway orchestra pit in its day, with an orchestration so rich that the players spread themselves between several instruments each. If there was one sacrifice, it was violas. There aren’t any. “But,” says Nézet-Séguin, “we’re hoping our sound and imprint … will give another color to the score.”

Tickets for Carnegie Hall: 212-247-7800 or carnegiehall.org. Tickets for Kimmel Center: 215-893-1999 or philorch.org. The New York concert will be streamed live, starting at 7 p.m., at WQXR.org.

Philadelphia Orchestra 2017-18 season highlights

The more enterprising meetings of soloist and repertoire are:

  • Oct. 12-15. West Side Story in concert is a bit of a wild card. The pitfalls of putting a Broadway show in a classical context are well documented by Leonard Bernstein's own later-in-life recording featuring opera stars in the main roles. Whatever happens, this will be interesting.
  • Oct. 19-21. Mahler's Symphony No. 1 is not likely to deliver any great surprises from principal guest conductor Stéphane Denève -- it's not that kind of a piece. But Jennifer Higdon's On a Wire concerto with the contemporary music group Eighth Blackbird shows how far the composer has evolved since her 2000 breakthrough, Blue Cathedral. A newer Higdon concerto for the orchestra's lower brass instruments arrives Feb. 22-24, 2018.
  • Nov. 2-4. Wynton Marsalis has written a Violin Concerto? Sure. The great jazz trumpeter has been writing concert works for decades, and this one features the glamorous Nicola Benedetti, who doesn't often play new pieces.
  • Nov. 16-18. Haydn's oratorio The Seasons arises infrequently, especially with the vocals assemblage that Yannick Nézet-Séguin has in store: Werner Gura and Matthew Rose, plus the young Swiss soprano Regula Muhlemann, whom the Guardian described as "a soprano with crystal clear tone you could pour over ice and drink."
    Feb. 8-10. Mirga Grazlynte-Tyla is the hot new name on the conducting circuit, and here, the 31-year-old Lithuanian collaborates on Mozart's Piano Concerto No. 23 with the great 90-something pianist Menahem Pressler (a frequent Philadelphia visitor since his 1947 debut).
  • March 8-10. Having just heard Michel van der Aa's beautiful, heartbreaking opera Blank Out at New York's Park Avenue Armory, I look forward to hearing this composer in the more rigorous terrains of his Violin Concerto, played by the deeply poetic soloist Janine Jansen.
  • April 12-14. Much-idolized pianist Daniil Trifonov continues his Rachmaninoff cycle with Piano Concerto No. 2 -- with Nézet-Séguin conducting. Enough said.
  • May 16 and 19. The Metropolitan Opera's new golden girl, Sonya Yoncheva, heads the cast in a concert version of Puccini's Tosca conducted by Nézet-Séguin.