Sugarland's 'Love on the Inside [Deluxe Fan Edition]' marks the duo's first-ever debut atop the Billboard Country Albums chart -- and their first chart-topping album ever. With sales of 314,000 copies last week, the duo's third release also bows at No. 2 on the Billboard 200, just behind Miley Cyrus' 'Breakout,' which sold 371,000 copies.

Sugarland's previous chart peak was at No. 4, with their 2006 release, 'Enjoy the Ride.' 'Love on the Inside' also enjoyed the best sales week of any country album since the Eagles' 'Long Road Out of Eden,' which moved 359,000 units in its second week of release in the fall of 2007.

Kristian Bush says that part of the key to Sugarland's success is the diversity he and partner Jennifer Nettles strive for with each new release, rather than finding a particular niche and sticking with it.

"Eventually what you get is: I can't figure out which George Strait record to buy because I don't know which song is on which record," Bush tells The New York Times. "All 50 of them are great, but you can't tell them apart. Where we grew up, you really knew the difference between this Police record and that Police record, or this Madonna record and that Madonna record. When you're 13, 14, 15 years old, you're taught that as a listener, so you can't help but try to do it yourself when it's your turn to step up."

The Deluxe Fan Edition of 'Love On the Inside' could possibly be bumped out of the No. 1 spot next week . . . by its regular version, which was released yesterday.

[Buy 'Love On the Inside' on iTunes]