Pianist Horacio Guttie'rez has built a substantial reputation primarily in the virtuoso romantic repertoire, which he handles with precise, exuberant technique, rich emotional expression and sure-footed musicianship.

Last night, for the opening concert in the Mostly Mozart Festival's third and all-too-brief summer season at the Kennedy Center, he turned to a work that is most clearly an 18th-century ancestor of that repertoire: Mozart's brilliant, mysterious and moody Piano Concerto in D minor, K. 466.

Although it looks ahead to Beethoven and, beyond him, toward Liszt and Tchaikovsky, this concerto presents the soloist with a strikingly different set of challenges. Written for a piano that had a much more restricted range of pitch and dynamics than the modern Steinway or Bo sendorfer, it states its points quietly and wistfully at many points where a later composer might simply roar; it suggests more than it actually says, and it never allows its obvious emotional intensity to undermine its basic air of polite decorum. The tensions it generates are unique, and so are its challenges to the pianist.

Guttie'rez met these challenges with aplomb, and he seemed to take the Mostly Mozart Festival Orchestra along with him. After a rather listless beginning, the orchestra generated considerably more vitality in its playing, a more cohesive ensemble sound and greater refinement of phrasing after the piano's first solo statement. These qualities clearly echoed those set forth by the soloist.

In a program that was mostly masterpieces, the orchestra and conductor Gerard Schwarz saved their best performance for the end, concluding with a bright, energetic, exquisitely phrased performance of Mozart's great Symphony in D, K. 504 ("Prague"), sensitively paced and as kaleidoscopic in its expression as the music itself.

The program opened with the slight, charming Symphony No. 1 in D of Carl Philipp Emanuel Bach--a work neatly poised between the baroque and classical styles, not quite a masterpiece but a most engaging confection and fascinating as a sample of the kind of music that led up to Mozart.

A minor but authentic masterpiece (as well as a brief departure from D as a tonal center) was Haydn's genial, lyrical Trumpet Concerto in E-flat, played brilliantly, stylishly and with readily communicated enjoyment, in spite of a few small intonation lapses, by trumpeter Stephen Burns.