It’s not often that a 12-minute piece by a living American composer proves to be the musical highlight of a two-hour concert of classical favorites. Usually the “modern” piece is that cacophonous thing that you grin and bear to get through to the good stuff. But at Friday’s season-opening concert by the Kansas City Symphony, it was the accomplished performance of Christopher Rouse’s Rapture, composed in 1999-2000, that made me happy to be in the Lyric Theatre again after a long summer. The concert, which also featured guest pianist Yefim Bronfman and music director Michael Stern, was an auspicious beginning to the conductor’s fifth season here, despite stretches of ennui in the big Austro-Germanic works flanking the Rouse. It also highlighted several new players, including associate principals in the clarinet, bassoon, horn and percussion sections, who were playing their first concerts with the ensemble.

Rouse, 60, is a Baltimore native who teaches at the Juilliard School and is widely celebrated. I have made no secret of the fact that I consider him perhaps the most solidly musical American composer working today. Earlier this year Musical Americacapped his long career of honors and distinctions, which has included a Pulitzer Prize, by naming him its Composer of the Year. Rouse (rhymes with house) has won great critical and public acclaim, especially for his orchestral scores, and his works have been commissioned and performed by all the major American orchestras. Yet he still remains too-little known by concert audiences who are perhaps more likely to have heard music by the “three Johns” of American music — Adams, Corigliano and Harbison.

Rapture is well summed-up by its title, as the visiting composer remarked from the stage before the performance, a sort of paeanto bliss and extreme emotional fervor. Musically it is like a miniature “concerto for orchestra,” with passages that brilliantly and often unexpectedly highlight strings, woodwinds, timpani (a rapid-fire duet for double timpani), brass, percussion. Beginning from a low rumble that resembles the opening of Also sprach Zarathustra, the piece builds momentum gradually through a series of ebbs and flows, with beautifully gauged stealth. Its harmony is lushly tonal, while its textures demonstrate the composer’s sophisticated orchestral mastery. There are subtle nods to a whole host of 19^th-and 20^th-century composers. Stern conducted with clarity and command, and showed off just what a good piece this is. Rapture closes with huge swelling waves of sound, and on Friday the audience demonstrated its approval afterward with a hearty ovation: A number of listeners were on their feet, in fact.

The program had opened with Haydn’s Symphony No. 49, La passione, an expression from the composer’s Sturm und Drangyears, during which he wrote several works containing stormy emotional content. In concept it made a worthy pairing with Rouse’s passionate piece. Stern led with conviction, and the string sound had a pressing earnestness. But there was often a sense of rote, a lack of shaping and rigidity of pulse that made this white-hot piece feel oddly mechanical.

The program’s second half was devoted entirely to Brahms’ nearly hour-long Second Piano Concerto. Bronfman played with the signature sureness of touch, technique and rhythmic drive for which he is famous. Nevertheless the one word that kept coming to mind was “reliable.” To be sure, one wants reliability in a pianist for Brahms’ Second, but one wants more. Bronfman showed in some of the softer passages that he was capable of a sweet transparency and delicacy, but in general there was a sort of a routine quality to the playing, which often seemed distant and detached from the concerto’s fiery core. The orchestra performed with gusto, however, and principal cellist Mark Gibbs played his famous slow-movement solos with plaintive warmth.

The Symphony’s performance is repeated on September 26 and 27. For tickets call 816-471-0400 (on weekdays and Saturday mornings), or for 24-hour ticketing go to kcsymphony.org.

To reach Paul Horsley, performing arts editor, write email to phorsley@sbcglobal.net.