Time to grow your manes back, boys, and rejoice: the haircut years are over. Last Sunday at Gillette Stadium, Lars Ulrich was Metallica’s only shorn member, and the band played the best set I’ve seen in 14 years. They did just three songs written after 1991 (the title track and "Frantic" from the new St. Anger, and "Fuel" from ’97’s Re-Load), choosing instead to focus on classic material. The first 45 minutes were devoted to top-speed renditions of "Battery," "Master of Puppets," "Harvester of Sorrow," "Welcome Home (Sanitarium)," and "For Whom the Bell Tolls": five songs in 45 minutes, not a radio hit among them. It was a return to the dense, laboriously plotted, and rhythmically vexing æsthetic that established the band as metal’s most adventurous soldiers in the ’80s. "It . . . is so . . . good . . . to see you," James Hetfield sighed a couple songs into the set. "We’ve missed you." We’ve missed them, too.

"This one’s for all you people who stuck with Metallica through the tough and shitty times," Hetfield added before launching into "Harvester," . . . And Justice for All’s brooding eight-minute centerpiece. "Been cheated of my youth," he snarled, and if that line once referred to the encroachment of adult concerns — imminent apocalypse, political repression, teenage drug wastelands, religious hatemongering — on young minds, it also fit a band who seemed to have lost track, for the better part of a decade, of who they were. Somewhere, former bassist Jason Newsted is probably wondering why they couldn’t have done this five years ago, but newcomer Robert Trujillo (formerly of Suicidal Tendencies and Ozzy Osbourne) fit in so well that the band gave him a bass solo, even if they still flashed the late Cliff Burton’s picture on the monitors while he played it. "Frantic" and "St. Anger" sounded bulkier, chunkier, and speedier, easily eclipsing the album versions.

The second half of the two-hour set was just as invigorating as the first — reaching back to Kill ’Em All (Metallica’s albums are all released by Elektra) for a back-to-back "No Remorse" and "Seek and Destroy," then closing out with Justice’s harrowing opener, the nuclear-winter nightmare "Blackened." Throughout a long, hot afternoon, the "Summer Sanitarium" opening bands — Deftones, Linkin Park, even Limp Bizkit, who reprised their MTV Icon version of "Sanitarium" — demonstrated their fealty to the old masters. But Metallica played with the conviction of a band who know they have to prove themselves all over again. After seeing them do vintage Metallica at the tour’s European opener last month, Anthrax’s Scott Ian told the band’s Web site, "It’s like getting to see Olivier play Hamlet, or Jordan play basketball, or Ali fight." If Metallica are re-auditioning for the role of world’s greatest heavy-metal band, they’re off to a good start.