If you had come to me 20 years ago and said‚ "In 2008‚ Ricky Skaggs and Bruce Hornsby are going to play live together and do some of the best bluegrass you've ever heard‚" I would have told you to stop eating peanut butter-and-anchovies pizza before bedtime‚ because your dreams were getting bizarre! That's why it was a definite WTF moment when Skaggs and Hornsby stepped onto the stage at the packed-and-sweltering Music Hall‚ pausing to check their hair in a compact makeup mirror Hornsby pulled from his pocket.

"Oh‚ killin'‚" Hornsby assured him. The crowd laughed‚ loving the playful banter that would reappear throughout the two-hour-plus set. Then the band started playing and the laughter stopped‚ because there was nothing funny about the white-hot‚ pedal-to-the-metal bluegrass music that filled the Hall like water from a dynamited dam.

Going back to his bluegrass roots was the best decision Skaggs ever made‚ and from his nearly constant smile‚ he knows it. He played rapid-fire mandolin on "Bluegrass Breakdown" and "Toy Heart" -- two tunes from Honoring the Fathers of Bluegrass (Skaggs Family‚ 2008)‚ his tribute to the late-1940s music of Bill Monroe‚ Lester Flatt and Earl Scruggs -- and Skaggs' voice is as high and strong as it was when "Country Boy" was the crossover hit of 1985. The honey-sweet harmony he and Hornsby made with guitarists Ben Nelson and Paul Brewer was stunning from the start‚ and never wavered.

Hornsby's musical fearlessness is well-documented: He's the last surviving keyboardist for the Grateful Dead (which‚ for better or worse‚ has become synonymous with playing drums for Spinal Tap)‚ and he cut a burning jazz disc last year with Jack DeJohnette and Christian McBride‚ two of the genre's fiercest monsters. Even so‚ the concentration Hornsby brought to every piano solo was truly impressive. Two factors may have been behind that: While he and Skaggs have worked together since 2000‚ there was still the chance Hornsby could be seen as a "gadget player" in the band‚ so he had a thin tight-wire to walk (which‚ for the record‚ he did flawlessly); what's more‚ though Hornsby doesn't get anywhere near the love he deserves as an instrumentalist‚ he was surrounded on this night by players that were as good as him‚ if not better.

Most of the members of Kentucky Thunder look like they were in grade school when Skaggs and Hornsby had their respective success in the '80s. And yet‚ the virtuosity they all displayed could have come from players with the same length-of-service as the two stars they were backing up. Andy Leftwich's fiddle was steeped in the tradition of Vassar Clements‚ and lead guitarist Colby Kilby and six-time Banjo Player of the Year Jimmy Mills easily matched Skaggs' instrumental intensity. The three support players helped move Hornsby's mega-hit "Mandolin Rain" into a darker‚ more mournful space‚ and they traded lightning-fast solos with Skaggs and Hornsby on Doug Kershaw's "Sally Jo"; if it had been a tennis match‚ someone in the audience would have snapped their neck.

Above all‚ this was a fun show! Skaggs and Hornsby sang about the positives and negatives of ice cream on "The Dreaded Spoon"; they invited audience members to come onstage and clog during "Sheep Shell Corn" (seven people volunteered); and you have not lived until you've heard a bluegrass band sing the lyrics to Rick James' "Super Freak." ("She's a very kinky girl/The kind you don't bring home to Mother…" You get the idea.) It all ended with a righteous version of Monroe's "Pig in a Pen‚" bringing smiles to everyone who remembers the Dead offshoot Old & In The Way.

More than just a meeting of great musicians‚ we witnessed a moment in a relationship that started out as collaboration and developed into lasting friendship and enduring respect. It just goes to show: Peanut butter-and-anchovies pizza may be disgusting‚ but the clairvoyance it can give you is phenomenal!