She later recorded the "Exsultate, Jubilate" along with the "Great Mass in C minor" under Leonard Bernstein, in 1990. On December 5, 1991, the bicentenary of Mozart's death, she sang his "Requiem" with Cecilia Bartoli, Vinson Cole, René Pape, and the Vienna Philharmonic conducted by Georg Solti in St. Stephen's Cathedral, Vienna. By this time Auger was already developing a malignant brain tumor without her knowledge. Suffering from recurrent headaches, her strict diet routine (she used to not eat anything from the night before her performance, save for water) in part made her oblivious to her own sickness.