The standing ovation at the Metropolitan Opera began 10 minutes before the show began.
When retired soprano Birgit Nilsson walked into her first-tier box seat before Saturday's performance of Wagner's "Tristan und Isolde," the entire audience -- including the orchestra -- rose and gave her a 45-second standing ovation.
Saturday was the 40th anniversary of Nilsson's Met debut, which was as Isolde, and the 81-year-old singer was in New York this week to give master classes for the Met's young artists development program.
During the first intermission of the performance, Nilsson condemned the recent installation of microphones to enhance voices at some opera houses, including the New York City Opera on the other side of Lincoln Center Plaza.
"It is like doping with the sportsmen," she said.