LENOX -- Rafael Fruehbeck de Burgos led the best Boston Symphony Orchestra concert of the weekend Sunday afternoon.
The first half was repeated from the Symphony Hall season, three of Brahms's relatively neglected works for chorus and orchestra, ''Naenie," ''Song of the Fates," and ''Song of Destiny." The music is noble and multi-dimensional, and so was the conducting, playing, and most of the singing from the Tanglewood Festival Chorus -- though there was a little uncharacteristic instability in the soprano section.
For the second half, the Spanish conductor chose Beethoven's Fifth Symphony, which, almost unbelievably, hasn't been played by the BSO at Tanglewood for a decade. Fruehbeck reportedly rehearsed it as thoroughly as if no one had ever played it before, as if it were a world premiere, and the results showed. The performance was as weighty, lithe, and dangerous as a tiger; it had fearful symmetry, and claws.
Sir Neville Marriner presided over a civilized all-Mozart concert Saturday night, conducting spruce, sprightly performances of the overture to ''The Marriage of Figaro" and the 39th Symphony.
The young American pianist Jonathan Biss brought style, taste, and imagination to the A-Major Piano Concerto, K. 488. The playing was perhaps a bit small-scale for a 5,000-seat venue; Biss did everything right, but one wanted a bit more of everything. He was also classy and nimble in the piano part Mozart composed for himself to play in the concert aria ''Non temer, amato bene."
This was not very successfully sung by Veronique Gens. After beginning her career singing baroque music in Les Arts Florissants, the French soprano emerged a few years ago as a leading Mozart singer. At her BSO debut one could admire her tall and striking presence, and her lustrous timbre.
But she did not seem well prepared for her two concert arias, referring often to the printed music on a stand at her side. She hadn't worked either one of them into her voice and made no effort to enter the drama of the situations. She got through the music, but that's about all.
Mozart deserves nothing but the best, and Tanglewood is not Podunk -- there were students in the audience who have spent the summer absorbing the highest ideals of the profession. Gens all but phoned it in, so she should be ashamed of herself.