In front of a packed house Sunday at the Marcus Amphitheater, country/pop duo Sugarland put Summerfest 2011 to bed with fan-focused energy and sassy sweetness.

Touring on the back of their latest album, "The Incredible Machine," Jennifer Nettles and Kristian Bush mixed a wonderful combination of music from their latest album, older cuts and even a few cover songs into the set.

Leading off with their new single, "All We Are," they got the crowd pumped to transition into their song "Stuck Like Glue," a performance bound to stay in the heads of all in attendance until the next time Sugarland rolls into town.

Putting the 19th century warehouse staging aside, the duo relied heavily on the work of its vocals and the supporting musicians in contrast to some of the acts that graced the same stage earlier in the week.

The two have not radically changed their show since their early days when they were playing more humble gigs, like a post-Admirals game performance in 2006. Then and now, they still sing the loudest on "Baby Girl," a song about working their way up to stardom.

Nettles' powerful delivery of "Stay" never wavered and garnered some of the loudest cheers of the night. They did not stay on the serious songs for long, pumping up the crowd with "Find the Beat Again" and a cover of "Sweet Caroline."

Bush stood in for Jon Bon Jovi on "Who Says You Can't Go Home" and made a few young fans' night by personally delivering an autographed guitar back to the covered yellow seats.

As part of "Everyday America," they sampled Ce-Lo Green's "Forget You," Britney Spears' "Hit Me Baby One More Time," Dolly Parton's "9 to 5" and even Beyonce's "Bootylicious." The party wouldn't stop there, in the encore they did their own "Stand-up" and Dexy's Midnight Runners' '80s classic "Come On Eileen."

Sara Bareilles, as the opener, could kill you with the kindness she put out to the audience in doing her due diligence in getting the crowd ready. She gave strong vocal performances of her hits,"Love Song," "King of Anything" and "Uncharted."

Standing at the piano for the majority of her half hour stint on the main stage, Bareilles may not have been an obvious opening act for Sugarland, but certainly matched the personality of the headliner.