Filling in for Mattila will be Christine Brewer, the widely admired dramatic soprano. This will be Brewer's third high-profile substitution in little more than a year: she replaced Deborah Voigt in an acclaimed Beethoven Missa Solemnis with Levine and the BSO in January 2006, and last July she jetted to California to fill in for Ren_e Fleming at the gala finale of the first Festival del Sole in the Napa Valley.

More recently, both ladies figured in a critics' list, published in the current issue of BBC Music magazine, of the top 20 sopranos of the recording era: Mattila was ranked at no. 15, with Brewer at no. 17.

Brewer will join tenor Johan Botha (Florestan), tenor Matthew Polenzani (Jaquino), bass Robert Lloyd (Rocco), bass-baritone Albert Dohmen (Don Pizarro), soprano Lisa Milne (Marzelline), and bass-baritone James Morris (Don Fernando), along with the BSO and the Tanglewood Festival Chorus, for three performances of Fidelio: Friday (March 23), Sunday (March 25) and next Tuesday (March 27). More details are available at www.bso.org.