The leading man is sick. The understudy goes on. The show is saved. A star is born. It wasn't like that on Monday.

Ben Heppner, one of the few singers equal to the demands of Wagner's Tristan, reportedly was suffering from a virus. A Canadian tenor named John Mac Master took his place. His only previous experience with the company involved a couple of Pagliacci s in 2005, but he did survive a recent run of Tristans in Wales. He deserves credit for bravery under pressure. Unfortunately, his voice, essentially gruff and throaty, virtually gave out before the five-hour marathon drew to a merciful close. And, squeezed into a bizarre Samurai costume, he had trouble projecting a romantic illusion - even in a staging scheme that frequently favours singing silhouettes. Not incidentally, Dieter Dorn's odd-mod production, designed in 1999 by Jürgen Rose, imposes constant distractions: a cyclorama that changes colours like a demented jukebox, phallic towers that rise and fall on cue, characters that clamber in and out of trap doors and boxes, and pop-up toys that pretend to symbolise delirium.