All performances of the German composer's mammoth five-hour epic romance were originally to have been sung by Ben Heppner, believed by many to be the leading Tristan of our time, and Deborah Voigt, one of the world's most celebrated Wagnerian sopranos. As is sometimes the case in such a physically grueling profession, this has not been so.

An early indisposition of Mr. Heppner forced him to bow out prior to opening night. That performance was sung by fellow Canadian tenor John Mac Master.

American tenor Gary Lehman assumed the role for the March 14 performance. Lehman gained considerable attention in 2005 when he stepped in for Placido Domingo in the title role of Wagner's Parsifal at the Los Angeles Opera. In addition to marking his Met debut, Friday night was his first time performing Tristan anywhere.

Remarkably the cast changes were not to end with the curtain rising. During this very same performance, Voigt took ill in the middle of the second act and the performance was halted for approximately 15 minutes. Dramatic soprano Janice Baird was waiting in the wings and stepped in for Ms. Voigt to finish the show. Voigt returned for the March 18 evening show, with Lehman repeating as Tristan.

At this Saturday's matinee - to be transmitted in high definition to movie theatres around the world - Robert Dean Smith will step into the male lead, a role he has performed with the Bayreuth Festival, the Vienna State Opera, and Madrid's Teatro Real. Mr. Heppner still hopes to return for the final two performances on March 25 and 28.

Also in the cast are Michelle DeYoung as Br‹ngane, Matti Salminen as King Marke, Eike Wilm Shulte as Kurvenal and Stephen Gaertner as Melot.

For more information and tickets visit www.metopera.org

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All photos by Ken Howard for the Metropolitan Opera.

Deborah Voigt as Isolde and Michelle DeYoung as Brang‹ne		Matti Salminen as King Marke

John Mac Master and Deborah Voigt in the title roles

Deborah Voigt as Isolde		Michelle DeYoung as Brang‹ne (above) and Deborah Voigt as Isolde

Deborah Voigt as Isolde		Michelle DeYoung as Brang‹ne (above) and Deborah Voigt

Michelle DeYoung as Brang‹ne and Deborah Voigt as Isolde

Gary Lehman and Janice Baird in the title roles at the March 14 performance		Deborah Voigt as Isolde

Deborah Voigt and John Mac Master