BY ROBERT DEAN LURIE

Robert Plant is one wily old coot. He seems to take mischievous glee in sidestepping expectations, and it's a testament to the man's originality that it's almost impossible to pigeonhole him into a genre. Hard rock? That may fit Led Zeppelin's Presence or his solo album Manic Nirvana, but it's a woefully inadequate label for Raising Sand, his collaboration with bluegrass musician Alison Krauss. Americana? Try pinning that on the Portishead-inflected Mighty Rearranger.

This summer, when most other professional musicians can't even make a living performing their hits on the road, Plant is touring around the country with a ragtag ensemble called Band of Joy, playing songs from an album that will not be released until September. Compounding the weirdness is the fact that Band of Joy was the name of Plant's pre-Led Zeppelin group with John Bonham. He claims that this new group, featuring alt-country guitarist Buddy Miller and singer Patty Griffin, is continuing in the same free-form vein of its earlier incarnation. We'll have to take his word for it because the original Band of Joy never released an album.

It's safe to say that audience expectations for Plant's July 20^th performance at the Dodge Theatre in Phoenix were all over the map. Certainly there was a contingent expecting an extension of the Raising Sand sound, but there were also a lot of drunken idiots wearing those black Led Zeppelin T-shirts you remember from high school. This is what Robert Plant goes up against every night, thirty years after his most famous band's demise. It's one of the most extreme examples of a double-edged sword you can imagine: Obviously, if it weren't for Led Zeppelin, Plant would not have the opportunity to be playing for a healthy-sized crowd in Phoenix at the age of 61. But Led Zeppelin is the only thing that many in that crowd want to hear. How to thread the needle?

Plant's solution, as it turned out, was to sidestep the issue entirely-for the first half of the set at least. He began with a trancelike version of "Down to the Sea" from his underrated 1993 album Fate of Nations. From there Band of Joy gradually opened up the drone to incorporate rock, folk and blues elements, recasting gospel hymns, a Richard Thompson number and - why the hell not? - "Monkey" by indie-rock trio Low in their own image. Buddy Miller held the whole thing down, negotiating his way through Arabic maqam scales, delta blues riffs, and lightning fast rockabilly licks with aplomb. Patty Griffin, pounding her guitar and wailing away at stage right, impressed equally. And Plant, in the middle, was an all-around class act. Voice as strong as ever, the occasional tonal climbs deployed with precision and taste. And at this late stage in the game we've been hit with another curveball: Planty is a dynamo on the washboard.

A good hour into the set the familiar opening riff of "Over the Hills and Far Away" got the audience to its feet. Fists pounded sky as guttural "Fuck yeah!"s exploded throughout the crowd like staggered firecrackers. Not so fast, lads; this was Zeppelin done Band of Joy style, with Miller building his own solos from the ground up, Griffin taking the high vocal parts that once belonged to Plant, and the sweet sigh of pedal steel arcing up behind them. It was more than the two beer-swilling Zepheads seated next to me could bear. They got up and made their way to the aisle. One of them turned to me, deep lines of sorrow furrowing his brow, and sniffed, "We won't be back."

These gentlemen were hardly alone; but the thing is, Band of Joy were just so damned good that they managed to win most of the audience over anyway. By the end of the evening, another drunken guy behind me started bleating, "BAND OF JOY! BAND OF JOY! BAND OF JOY ARE FUCKING KILLING IT!" Indeed.

It was a remarkable evening. Leaving the Dodge afterward, I felt like I had just attended a crash course on the past, present, and future of popular music, presided over by a lanky old English hippie. In terms of ambition and breadth, this tour is without peer. Sure, you can go watch Lady Gaga change her costume 14 times, but if you want to see a band change genres just as often and - this is the important part - love every minute of what they're doing, you owe it to yourself to catch one of these shows.