Since the mid '80s, the debate had raged between Van Halen fans: Sammy or Dave? Fans got to judge for themselves when the band's two former singers teamed up for a co-headlining tour that turned out to be highly contentious.

Over the course of a 21-date run, audiences could decide each night who was the better frontman. Would it be David Lee Roth, the original, high-flying wordsmith who left the Southern California party band in 1985 following the tour for the mega-selling 1984? Or his replacement, former Montrose singer Sammy Hagar, who struck solo gold with "I Can't Drive 55" and had some of the best pipes in the business?

When  the new millennia dawned, both singers had fallen out of favor with the Van Halen brothers. Hagar left in 1996, and the band brought back in David Lee Roth, ostensibly for just two songs to be added on to an upcoming greatest-hits package. The majority of fans were hoping for a full-fledged reunion of the classic lineup, but it fell apart in spectacular fashion before former Extreme singer Gary Cherone was brought in for the ill-fated III album, which came out in 1998. Vocalist No. 3 departed the following year under amicable circumstances, and Van Halen tried working with Roth again – twice according to reports – but nothing ever came of it.

With Van Halen having been out of the public eye since late 1998, Hagar and Roth pulled one of the most audacious and implausible moves in music history, giving fans a chance to see them on the same bill as they teamed up for Song for Song, the Heavyweight Champs of Rock and Roll, a co-headlining tour that kicked off May 29, 2002, at Blossom Music Center near Cleveland.

“I was open to all sorts of crazy ideas,” Hagar said in his 2011 autobiography Red: My Uncensored Life in Rock. He and new manager Irving Azoff came up with the idea for the jaunt, “just to piss off Van Halen and get the fans worked up.”

Roth was amenable to the idea, having rejected an offer from Hagar to do a joint tour in 1997 and choosing instead to release a bestselling autobiography and greatest-hits album. "The time was wrong," Roth said at an April press conference to announce the union. "Now the time is right. It's completely unpredictable."

At the press conference, held at Sky Bar in Los Angeles, the contrasting personalities between the two were made immediately clear. Hagar’s more subdued demeanor was reflected in his red pants and yellow Cabo Wabo-branded T-shirt; Roth was clad in head-to-toe black and joined by Playboy Playmates the Dahm triplets, as well as a dwarf dressed as Andy Warhol.

"Sam and I are like fraternity brothers that have been through the same s----y hazing," Roth said. "There's a rivalry between us, so the audience gets the absolute best out of both of us. You have to think of it as two title fights with no under card. This is a co-headlining tour here. We'll flip a coin and the winner will headline opening night and then we'll flip-flop."

The coin flip took place the first week in May on Howard Stern's show, with Roth in attendance and Hagar calling in. The former won the toss, and would close the Ohio date, Hagar the next in Clarkston, Mich., and so on.

The set lists between the two would also be much different, with Roth focused primarily on Van Halen songs and one solo hit, “Yankee Rose,” while Hagar covered all eras of his career -- from his time in Van Halen to solo tracks. He was joined by then-Van Halen bassist Michael Anthony on some dates, and they even brought Cherone onstage for a few songs when the tour hit his hometown of Boston.

But the anticipated duet between Roth and Hagar never happened. “Right at the start, he rejected my suggestion that we sing a few songs together and make it a friendly thing,” Hagar said in his book. “He envisioned something more along the lines of WWF Smackdown.” In the book and in the 2003 DVD documentary Sammy Hagar & The Waboritas: The Long Road to Cabo, Hagar details how, at the stop in Michigan, Kid Rock tried to broker a deal between the two and get them onstage together.

"Kid rock is going, 'You guys gotta do one for the fans. I came here tonight wantin' to see you guys get onstage [and do] a duet. You're lettin' us down, you're lettin' the fans down,'" Hagar recalled in the documentary. "He brought up a wonderful point, you know? And I said, 'You're absolutely right. Let's talk to Dave.' And Dave is sitting there going, 'Well, sure Sam, let's do something then.' So Dave agrees, and I'm going, 'All right! The Kid put it together. Thanks Kid, you're awesome.'

"The next night, Dave goes, 'Aww, my throat's sore and I can't do it.' I went over to see him to say, 'Hey, let's work something out, what do you wanna do -- what song?' And he backed out of it. Then the next night he backed out of it. So finally it became a running joke, I used to go beat on his dressing room and he wouldn't even answer the door, and I'd say, 'Yoooo Diamond! You ready tonight? You ready to go out and do it?' You have to have a sense of humor about it."

That sense of humor would soon fade as the tour went on and the two traded barbs in the press. It got more and more heated and ultimately Hagar and Roth went to great lengths to avoid one another. “The Sam and Dave tour was a huge financial success,” Hagar said, “but a personal disaster.” Hagar accused Roth of cancelling a scheduled Sept. 2 show in Long Island by insisting that he would only play Madison Square Garden, and only if he could headline even though it wasn't his turn.

Ultimately, the final two dates of the tour -- in Buffalo and Syracuse -- were canceled, initially attributed to Hagar falling ill, but at the same time punctuating the failure of the experiment. The scrapped dates came in the wake of the pair appearing on the MTV Video Music Awards in a tense co-presentation of the award for Best Rock Video on Aug. 29. Later that evening, to make up for the cancelled NYC date, Hagar performed a free show at the much more intimate Irving Plaza, where half the tickets were distributed to the New York police and fire departments. Both Anthony and Cherone joined him onstage in what was, by all accounts, a raucous party.

Shortly after the tour, which was called “Sans Halen” by some writers, Hagar seethed to Guitar World that he would never tour with Roth again. "Boy, I hate to ever say I'm sorry I did something, so I can't say I'm sorry I did it," he said. "But I certainly wouldn't do it again, let's put it like that."

Hagar ended up with Van Halen again in 2004, recording three songs for the two-disc greatest hits-package The Best of Both Worlds and hitting the road for an 80-date tour, which, according to the singer, couldn't have gone any worse.

"It was the Sam and Dave tour all over again, only it was Sam and Eddie," Hagar said in his autobiography. "[Management] kept us apart as much as they could. We flew in different jets. We stayed at different hotels. We had out own limos. They had their bodyguards. Mike and I had ours. I stayed in my own dressing room on the other side of the hall. The only time I saw that guy was when we stepped out onstage."

Suffice to say, the reunion didn't last, barely making it to the end of the tour. In early 2007, there were once again rumblings that Roth was back in Van Halen, which wasn't the only surprise; Anthony was ousted in favor of Eddie Van Halen's son Wolfgang. In April that year, the band was inducted into the Rock and Roll Hall of Fame in the most Van Halen way possible: Hagar and Anthony -- two guys who weren't even in the group anymore --were the only ones on hand to accept the honor.

Van Halen did end up reconvening with Roth in the fall of 2007, without Anthony, for a successful tour that stretched to summer the following year. A new studio album, A Different Kind of Truth, came out in 2012 with a supporting tour that extended to Japan and Australia. In 2015, the band returned to the road for 41 dates across North America.

Time seems to have softened the headache of the Sam & Dave tour. In early 2017, Hagar said the only way he would reunite with Van Halen would be if they toured with both singers. "I think the fans would die and go to heaven," he said. “The competition for that would be great; he’d do ‘Panama’ and ‘Runnin’ With the Devil,’ and I’d be going, ‘Damn! I gotta step it up!’ I’m up for it.”

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