Pianist Jeremy Denk returned to the St. Paul Chamber Orchestra in a unique ­concert combining both chamber and orchestral music. The program, heard Friday night at Ordway Center, featured the Brahms Piano Quintet in F Minor and Mozart's Piano Concerto No. 25 in C Major.

Denk has been a favorite with SPCO audiences since his debut with the orchestra in 2002 and this is his fourth ­program in the past three ­seasons. His star shone in the Mozart, but he played with much humility in the Brahms.

In the first movement of the Brahms, concertmaster Steven Copes and associate concertmaster Ruggero Allifranchini used warm, vibrant tones to spin out the haunting melodies. Denk was overly self-effacing here, adopting almost an accompanying role. It would not have hurt him to have been more assertive.

But the musicians, including violist Maiya Papach and cellist Peter Wiley, gave the crashing climax the resounding depth of a much larger ensemble.

In the lyrical Andante, the tempi seemed to sag. A bit more rhythmic propulsion would have been welcome. They captured the energy of the Scherzo, playing alternately with nobility and intensity.

From the opening plaintive theme on the cello, the finale devolved into a dramatic rhythmic clash that brought it to a tempestuous conclusion.

The Piano Concerto No. 25 is one of Mozart's most serious, with a pervasive sense of ­struggle. Even his manuscript showed signs of agitation and frequent revisions, unusual for him.

The orchestra captured the first movement's sliding back and forth between "certainty and uncertainty," as Denk described it in a literate and ardent introduction.

He was in full command here. The piano's scales and arpeggios, usually designed as mere decoration, in Denk's hands sounded violent and anxiety producing.

He demonstrated his ­evident love for the concerto in his delicate performance of the idyllic Adagio. What it lacked in profundity, it made up for in joy.

William Randall Beard writes about music and theater.