Drummer Lars Ulrich suffered a "medical emergency" yesterday just prior to Metallica's performance at the U.K.'s Download 2004 festival in Donnington. But the metal vets forged ahead without Ulrich, enlisting Slipknot's Joey Jordison, Slayer's Dave Lombardo and Ulrich's own drum tech to fill in for a full set.

The eleven-song set opened with a pair of Metallica classics - "Battery" from 1986's Master of Puppets and "The Four Horsemen" from 1983's Kill 'Em All -- with Lombardo behind the kit. Jordison, clad in his Slipknot mask, drummed on eight of the remaining songs, with Flemming Larsen, Ulrich's drum technician, handling "Fade to Black." "Nothing Else Matters," "Enter Sandman," "Creeping Death" and "Seek and Destroy" were among the other songs played, all of which were listened to on CD and rehearsed shortly before Metallica had to take the stage. "When their backs are against the wall, they will always, always deliver," wrote Steffan Chirazi, editor of So What!, a Metallica magazine.

No further word has been given as to Ulrich's condition.