(NASHVILLE SKYLINE is a column by CMT/CMT.com Editorial Director Chet Flippo.)

When rock critics around the U.S. rush to endorse a new country act, that's usually a bad sign for country music. That's because it usually means that it's not real country music. In the case of Big & Rich, though, I can see it's a logical thing. There are some solid reasons why this unconventional debut CD enters the Top 10 of the Billboard 200 this week at No. 6. On the country albums chart, it trails only fellow Muzik Mafia member Gretchen Wilson's chart-topping debut.

What it mainly means is that it's music that rock and pop critics and audiences can understand because Big & Rich's work is shot through with passing hip-hop and rock and enough country cred and humor to snag a fairly wide audience. And a Skynyrd beat doesn't hurt.

This flag bearer of "country music without prejudice" -- as B&R dub their movement -- has sold almost 400,000 CDs in 10 weeks with virtually no radio play. CMT play and a slot on the Tim McGraw tour have spread their message.

It's not the first time this kind of musical experimentation has been tried in Nashville, and it certainly won't be the last. The most recent such hybrid was the late, lamented GrooveGrass movement from the '90s. Music producer and experimenter Scott Rouse put funkmeister Bootsy Collins together with such roots music pioneers as Doc Watson, Del McCoury and Mac Wiseman in an inspired vision of a spectacular musical fusion. Collins, a funk visionary who went from James Brown's band to starting Parliament/Funkadelic with the equally inventive George Clinton, brought a funk groove that transformed bluegrass into another plane, another dimension.

The result was an infectious blend of country, techno, funk, blues and bluegrass that still managed to be hardcore, credible music. The one and only GrooveGrass Boyz album, Groovegrass 101 (Reprise) remains a personal favorite. Imagine "Blue Moon of Kentucky" or "Little Cabin on the Hill" with Bootsy, Mac, Del and Doc and a techno buzz supercharging it.

GrooveGrass even had a mission statement: "We love traditional American music and want to insure its legacy is passed on to the next generation by putting it into a form that is palatable to modern popular culture. We're not trying to change any of these styles of music, we're just trying to get them to a generation that doesn't know they exist."

GrooveGrass had the musical chops solidly. What it did not have in order to survive was the visual thing, the hip-and-happening live aspect of Big & Rich and the musical theater ensemble the Muzik Mafia have. GrooveGrass wasn't young and sexy and TV-ready. It's that shiny allure and reckless energy that have propelled B&R to their present status. If they can ever fully capture all that on CD -- which they did with some success on the first CD -- then they could be unstoppable in pulling in a wide passel of fans. As it stands now, it's difficult to predict the future of such a movement.

Musical hybrids have come and gone, some with a lasting legacy, some with none. The Outlaw movement of the '70s profoundly and permanently changed the face of country music. The country rock exemplified by Gram Parsons' work with the International Submarine Band and the Byrds continues to inspire young musicians. Bands as diverse as Drive-By Truckers and Nappy Roots continue to push the limits of country and country rock.

I know I've said it before, but it bears repeating: One of the great appeals of country music is that it is indeed a huge tent that has room for a vast array of musical styles. There's enough tolerance for all kinds of music making. The fans will be the judges in the end.