Coinciding nicely with the new century — it was conceived in 1800 — the Piano Concerto No. 3 of Beethoven, which was given a lively reading at Avery Fisher Hall on Tuesday evening as part of the Mostly Mozart Festival, is the first piece of music to deify the creator-performer. Without this elevation of the auteur as the force majeure, there would be no piano concerti of Brahms or Schumann, Tchaikovsky or Greig, Prokofiev or Rachmaninoff. For the first time, the artist is at least the equal, if not the superior, of the amassed orchestral forces.

This is Beethoven the sonata writer at odds with Beethoven the orchestrator, a classic ego-id battle that remains magically unresolved; arguably, early 19th-century musical aesthetics appear in the movement’s energetic cadenza, with its left hand bursting through the rhythmic tension to drag us all, kicking and screaming, into a brave new world of conflict and resolution. One can imagine this larger-than-life composer-performer dominating the proceedings as no other had ever done before.

Romanian pianist Mihaela Ursuleasa gave a recital here a couple of seasons ago that I found lacking. Technically she is a wizard, but her idiosyncratic phrasing and recomposition of classical pieces left me more annoyed than edified. She seemed more interested in stating her own musical ideas rather than those of the composers on the program — a sort of Lorin Maazel of the keyboard. But perhaps one of us simply had a bad night. In this Beethoven concerto, she acquitted herself admirably.

From the outset, it was clear that Ms. Ursuleasa was aware of the historical aspects of this concerto, acutely feeling the personality clash that is its internal strength. She quickly established that she was giving a reading from a primer on pianistic touch. Her steely force was impressive, but even more inspiring was her ability to play softly.

And that cadenza: This necromancer opened emphatically, but then headed to the nether regions of the pianissimo, an ear-catching device that made this reviewer sit up straight in his chair. Her use of sotto voce increased the psychological tension tenfold, so that when the composer burst off of the printed page in a glorious double forte, Ms. Ursuleasa assumed a bardic role, communicating to us all the wild, atavistic core of this remarkable piano writing. Although some of the following notes were not those that Beethoven had written, overall this effect was jarringly memorable.

Maestro Osmo Vanska had the orchestra in top form, as he always does. This is the third year that I have heard him at this festival, and the band plays better for him by far than any other leader, including its own music director. Having restored the Minnesota Orchestra to its former glory days under Mitropoulos and Dorati, he has emerged as a rising star. Only his Finnish penchant for the contemporary will probably hold him back from a spot in one of America’s big five orchestras.

And he plays the clarinet as well, and led a spirited performance of the dark Mozart Serenade for Winds in C Minor, K. 388. If this is indeed a serenade, as the composer indicates, then at the very least there are dark storm clouds in the evening sky. In a Mostly Mozart evening that was actually mostly Mozart, the Symphony No. 39 rounded out the program.