In the event, audience expectations were more than rewarded: this was one of Dylan's good gigs, where his seat-of- pants approach paid handsome dividends despite his frequent attempts to bamboozle his band with erratic strumming and questionable singing. Dylan long ago embarked upon a policy of never singing the same song the same way twice, with widely variable results. On 'All along the Watchtower', the extreme nasality of his delivery acts like a kind of natural vocoder, a bizarre sound which has the perverse but welcome effect of reclaiming the song from Hendrix's version.
His 'Stuck inside of Mobile with the Memphis Blues Again' is a wild sub-operatic fantasia, and when he's joined by Morrison for a duet on 'The Irish Rover', flash-bulbs popping madly as rock's grumpy brothers come together over the same microphone, they appear to be singing in different keys. It's more hit-and-miss even than the Johnny Cash duet on Nashville Skyline, closer to Ornette Coleman's experiments in harmolody (which, roughly translated, means everyone playing whatever they want, with no regard for conventional harmonic relations).
When it works, though, this approach can transform a song, breathing new life into it. It's the vocal equivalent of off-road driving and it makes Dylan probably the premier extempore artist in popular music.
But it requires a band with uncommon alertness and sensitivity, able to switch styles mid- song and stretch out to fit any of Dylan's off-the-cuff alterations. And at the moment, he has such a band, equally at ease with a big fat Z Z Top boogie-style version of 'Maggie's Farm' or a country-rock 'Mr Tambourine Man' which heads off down Mexico way like his Pat Garrett & Billy the Kid soundtrack.
Mostly, though, the band favours the twin-guitar attack associated with the Allman Brothers or, more pertinently for Bob, with the Grateful Dead. When John Jackson's fluid, Jerry Garcia-styled guitar break sidles past Bucky Baxter's pedal-steel guitar and the gentle funk-rock backing of bassist Tony Garnier and drummer Winston Watson on a well-nigh unrecognisable 'Tangled Up in Blue', you're left thinking that this, surely, is how the dreary Dylan & the Dead album ought to have sounded.
Even Dylan, playing mainly electric guitar, gets to dash off a spikily effective solo on a version of 'Watching the River Flow' that's been reimagined as a Flying Burritos-style hill-billy hoedown. It looked more fun than usual for him, too.
Earlier, Van Morrison had brought his new, more relaxed approach to the proceedings, starting well with a jaunty 'Not Feeling It Any More' but then dissipating the mood with a succession of generic blues vamps. These would be fine for a small smoky club but were just whisked away on the wind here.
Morrison all but turned things round again with the concluding 'In the Garden' but overall it's clear that when the day is drizzly and overcast, Van's not really the man to brighten things up.