Sammy Hagar and Michael Anthony had already assembled one hell of a band for this summer's Best of All Worlds tour, which will celebrate their decade-long run together in Van Halen.

In addition to their Circle partner Jason Bonham on drums, the duo recruited guitar wizard Joe Satriani - another former bandmate, this time from Chickenfoot - to tackle Eddie Van Halen's famous and challenging guitar parts. The tour kicks off this Saturday in West Palm Beach.

But a fifth band member has been present in the social media video previews Hagar's been posting from tour rehearsals: multi-instrumentalist Rai Thistlethwayte, who's been a part of Satriani's touring band for several years.

For over 20 years, Thistlethwayte has been the lead singer and primary songwriter for the Australian pop-rock band Thirsty Merc. He also performs solo under the name Sun Rai and in jazz bands with a wide variety of artists.

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Hagar says Thistlethwayte has been a great addition to the group, particularly in terms of his vocal abilities. "I’m so happy to have Rai," he tells UCR. "He’s playing the parts and singing the background vocals. His voice sounds so good with Mike’s and mine. It sounds so much like the record, the vocals, more than anything. It’s above and beyond what I expected. I thought it was going to be good and we all had high expectations, but it’s chemistry, you know? You never know until you all get in there. Rai has a sense of humor. He’s really funny and he gets along with us. He can take a good punch, because you know, of course, we’re teasing him all of the time."

Thistlethwayte's guitar skills will also free Hagar up to focus on his own vocal duties more.  "You know, I hope the fans don’t get pissed. Because a lot of my fans want me to play more guitar," he continues. "But I don’t have to play more guitar. With him around, it’s like, there’s a couple of songs that I would have had to play guitar on, a couple of Van Halen songs that have two really distinct parts, especially during the solo. 'Summer Nights' has a minor 9 chord and it’s a real part of the song. Eddie starts off by playing that and then he overdubbed the solo and kept the rhythm part in there. So it’s really part of the song. Now, Rai’s doing it. If I had to sit there and play that thing, I’d be pissed. [Laughs] I’d be going, “Man, I’m strapped down here. I have to sit here and look at my shoes all night?” You know, Eddie’s guitar parts are not vocal friendly. It’s not easy, in the sense that you can’t play those parts and sing what I sing at the same time. I mean, I’m sorry, Jimi Hendrix would have been saying, 'No, fuck this!'"

Hagar says the band has rehearsed over 30 songs so far, with 90% coming from the Van Halen catalog. Hagar says trading pre-recorded tracks for a live keyboardist has been wonderful: "That’s really awesome. That’s the whole key now, it’s like, 'Wow, we can play this song, instead of sitting there and playing to a track.' It’s like people who use teleprompters. You know, I don’t use those, because I don’t like to read the lyrics to the audience. That’s like playing to a track [for me], it’s the same kind of vibe. You have to pay attention, but when everything’s live, we’re just playing together. Man, it’s above my expectations. It’s just really good. We’re kind of taking on a sound of our own. I mean, it sounds like Van Halen. My old stuff sounds like my old stuff, but it’s [all] just got a little bit of a different thing about it. It’s certainly more fun to play this way, I’ll tell you that."

Fans Can Expect a (Slightly) More Structured Sammy Hagar Show

Still, fans can expect a slightly less loose atmosphere at the shows, So Hagar and company can take advantage of their high-tech new stage and lighting setup. "We’ve got a big production. I spent a fortune on a production that we built for this thing," he explains. "The way the lights and everything are, it’s going to be a lot of automation, so things happen at a certain time to bring the magic. I usually don’t do that. I’ve been partying on stage since I left Van Halen. I haven’t had any structure, I haven’t had a set list, hardly at all. Mike and I just go out and we just fuckin’ party and the audience parties with us. That’s wonderful. We’re still going to do that, but we’re going to have to do a few things consistently, because I spent a lot of money to make magic happen. You’ve got to make sure that lightning strikes at the right time."

Van Halen Lineup Changes

Three different singers and two different bassists joined the Van Halen brothers over the years.