Anticipation is building for Fare Thee Well, with the latest appetite-whetting teaser coming out of Terrapin Crossroads in San Rafael, Calif.

Anticipation is building for the Grateful Dead's Fare Thee Well concerts with the latest appetite-whetting teaser coming out of Terrapin Crossroads, the San Rafael, Calif. performance space and restaurant owned by Dead bassist Phil Lesh. That's where, in the wee hours of May 1, Phish guitarist Trey Anastasio joined Lesh and son Grahame Lesh for a two-song jam of the Dead classics "Bertha" and "Goin' Down the Road Feeling Bad."

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A 10-minute video of the GTRFB cameo appeared online the morning of May 2 and was quickly shared by Dead-icated sites and social media. Naturally, Deadheads and Phish fans are weighing in on Anastasio's performance, seeing as he will join the Grateful Dead for five shows in the coming months (June 27 and 28 in Santa Clara, Calif. and July 3 through 5 in Chicago).

Our take: Anastasio is uncharacteristically timid at first, but settles into the groove and rides it, melding his trademark guitar crunch with a dose of psychedelia that winds around and fades out beautifully.

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To be sure, Lesh's Terrapin Crossroads is a bootcamp of sorts for players honing their solos amid the complex, snaking jams for which the Dead is known. And from what we hear, Anastasio has been rehearsing religiously -- on some days, playing as much as seven hours of Dead tunes.

It all bodes well for a stellar pair of warm-up shows miles away from the Dead's birthplace outside San Francisco.

Watch the video below: