For 18 years, Jeff Chimenti has had a rare view into the world of the Grateful Dead -- from the side. As longtime keyboardist for Dead guitarist Bob Weir's side gig Ratdog, the versatile musician has also sat in with bassist Phil Lesh for Phil and Friends, toured with Further Festival and accompanied drummers Mickey Hart and Bill Kreutzmann along with Phish guitarist Trey Anastasio for the historic Fare Thee Well concerts during the summer of 2015.

Now, as the year draws to a close, Chimenti -- a jazz musician who adds a melodic dazzle to the jams for which Dead shows are known -- returns to the stage with Dead & Company, the continuation of a 50th anniversary celebration run featuring Weir, Hart and Kreutzmann with John Mayer on guitar and Oteil Burbridge on bass.

Chimenti spoke to Billboard ahead of the band's two-night New Year's stand at Los Angeles' The Forum.

Billboard: What was your Grateful Dead experience prior to joining Ratdog in 1997?

Chimenti: None, honestly. I'm kind of ashamed to say it. Jazz was the world I was living in. That musical path never came into my existence. I kind of kick myself now, having to learn the [Dead] songbook and how much good music is there, [I think], "How did I miss this?" I never saw them live and I wish I had. But to be able to share it with them on stage now, it's been quite an honor over all these years.

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How was Fare Thee Well for you?

It was awesome. Just, wow. And probably about what I would have imagined to be the closest to a full-on Grateful Dead experience. Being able to see it from the side of the stage and looking out at that stadium crowd, it was a treat.

Once it was decided to continue on with Mayer and Burbridge as Dead & Company, how long did it take to gel musically?

It happened from gig one, and is continuing to grow, which is what we want. Obviously, during the rehearsal period, even though you're learning song forms and harmony, you try to jam... And we got into some moments there, too, but it really comes to life once you hit the stage. And there's no other way to find out -- you've got to jump into the fire and go for it.

When Billboard spoke to Mayer ahead of the tour, he was still finding some songs difficult to play. Have you seen him improve?

He's obviously a great player all around, and I think he's really found himself [with Dead & Company] by showing his versatility as a musician, performer and vocalist and making it his own. That's been a thrill for me. He's got big ears and is really fun to play with. So I think he's done a fantastic job, it's not easy.? Oteil has been killing it too.

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Are there songs that you struggle with?

Everybody makes mistakes -- it's all part of how you learn. I don't look at it as anything negative. You do the best you can and go day by day.

Are there songs that you find fun to play?

I'd say the same thing. On some days, there's a lot of stuff going on and I might have to work on an orchestration. It could be the simplest song or it could be the hardest song -- you just never know what's going to be the strongest during any given night. You could look at a set list but once a transition happens, it's, like, "Whoa, never saw that coming!" That's the beauty of it -- going in with an open mind and taking it night by night. And having conversations with your brothers up there -- that's really what it's about.

Is there a method to the magic of playing with this group of musicians?

With John, Oteil and myself, we all kind of came from the same boat -- not having background in [the Dead] -- but we do have the ability to immerse ourselves in anything. That was always my goal in coming at it from different genres. You have to be malleable, to pay attention and to listen. But you also have to put your emotions into it.

Will this be a one-off tour or could we possibly see a summer leg in the future?

Well, I certainly hope it will continue! I don't have any details, but if it's good and successful, why let it go? The music's got to carry on.

You are now the longest tenured keyboard player in the history of the Grateful Dead family [original keyboardist Ron "Pigpen" McKernan died in 1973 two years shy of 30; Keith Godchaux was killed in a car accident in 1980; and Brent Mydland died of a drug overdose in 1990]. Does sitting in the hot seat make you nervous?

I try not to think about that, especially since I have the same birthday as Brent Mydland, and I'm using his organ, so it's kind of weird... Our time is our time, and it's pre-written. You've just got to go with the punches while you're here. But so far I've broken the mold, and I intend to keep doing that for as long as they'll have me around.