There are piano concertos and then there are piano concertos.

Many in the genre could be more accurately described as orchestra works featuring piano or even works for piano accompanied by orchestra.

Not so with Brahms. In his two concertos he returned the form to a meaning closer to the probable root of the Latin "concertare," which has a wonderful double meaning of 'to debate' and 'to work together.' The pianist and the orchestra are both in competition and joined harmoniously.

Friday night, patrons of the Pittsburgh Symphony at Heinz Hall heard first-hand just what a struggle Brahms set before the pianist in his Piano Concerto No. 2 of 1881. The pianist, here the American Jonathan Biss, is in constant danger of being swallowed by a whale of an orchestra part, conducted by the deft Gianandrea Noseda.

Brahms wrote so magnificently for the orchestra that one could almost imagine the piece as a symphony, that is, unless the pianist can wrest some of it back. Mr. Biss was only partially able to do so. He is a fantastic pianist with whom the PSO is forging a relationship, but I am not sure he is ready for Brahms' Second.

Foremost was his lack of volume and weight, especially in the left hand and lower register. In my opinion, Brahms' Second should sound as if someone stuck a subwoofer on stage. The bass range should be prominent, but Mr. Biss never drove to the bottom of the key. But it's not just a case of being loud and heavy. A pianist here must wrench the work from the orchestra by making it follow him, especially at key moments, such as the spectacular descending melody in the second movement or any number of other thematic areas in the first and fourth. Instead, Mr. Biss tended to play along with the orchestra.

Mr. Biss certainly has the chops for the piece, despite a few slip-ups. His long arms and lithe hands bounded up and down the keyboard, and he has a preternatural ability to play melodic lines. But it just wasn't weighty enough. In this competition of a piece, score this one to the orchestra, with goals by horn player William Caballero -- an epic entrance in the first movement -- and cellist Anne Martindale Williams -- a burnished solo in the third -- and assists by many others.

Haydn's lesser-known Symphony No. 56 lies on the other side of the dynamic range. Composed in 1774, this work is light and graceful court music typifying what we now refer to as the classical period. Simplicity reigns, in surface textures and themes, but Mr. Noseda's energetic approach revealed a deep world below. The floating melody and harmony of the first movement are worth the other three combined, to my ear, especially when delivered with the sensitivity Mr. Noseda displayed. But principal bassoonist Nancy Goeres had something to say about that, with a bouncy solo in the second movement, echoed by oboist James Gorton.

The Haydn symphony was a PSO premiere, as was Liszt's "San Francesco di Paola" from "Legendes." In this case, it's easy to hear why. In the pantheon of tone poems by the genre's inventor, this one is definitely second tier. It tells the story of a lesser-known St. Francis and his miracle of sailing boatless to Sicily from Italy. The orchestra played it a bit ragged, and Mr. Noseda didn't coax the full, flowing sound from the PSO for which the water themes call.

The program repeats today at 2:30 p.m.

Critics Andrew Druckenbrod and Scott Mervis talk about music on "The Beat," available exclusively at PG+, a members-only web site of the Pittsburgh Post-Gazette. Our introduction to PG+ gives you all the details.