It was a night of jaw-dropping collaborations, surprises and new music at the 46th Annual Academy of Country Music Awards.

"Alright Mandalay Bay, ready to see a little music history?" Sugarland's Kristian Bush asked the audience before bandmate Jennifer Nettles and R&B/pop sensation Rihanna took to the Mandalay Bay Hotel & Casino stage.

And music history it was. Rihanna appeared alone in a knock-out white dress, singing the first verse of her new single, 'California King Bed' as Jennifer's vocals could be heard in the background. Soon, Jennifer appeared side stage and the two alternated singing lead and harmonizing throughout the remainder of the track. The vulnerable ballad showcased each artist's incredibly powerful vocals and was just one of the many unexpected collaborations of the night. [Watch video of the performance below.]

Brad Paisley kicked off the night of musical hook-ups at the MGM Grand Hotel and Casino with his current single, 'Old Alabama.' Wearing blue jeans, a black Alabama concert t-shirt and his classic white cowboy hat, Brad wowed the crowd with his guitar skills, then amped up his tribute to the iconic country band by having them join him mid-song. Amid screams, Brad and the band closed the song with a fast-paced guitar jam.

Throughout the night, performances alternated between the MGM Grand Hotel and Casino and Mandalay Bay Hotel and Casino.

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Getty Images

While Rihanna and Jennifer's performance may have been the most anticipated pairing of the night, it was Carrie Underwood and Aerosmith frontman Steven Tyler's set that really had jaws dropping. Carrie came out of the shadows, taking the stage in an uncharacteristic short black number -- complete with pink streaks in her hair -- to sing her uptempo country-rocker, 'Undo It.' During the second verse, the iconic rocker, clad in white from head to toe, appeared to deafening cheers. Carrie and Steven sang alternating lines of the song, then segued right into Aerosmith's hit, 'Walk This Way.'

Alan Jackson introduced the final collaboration of the night, Zac Brown Band and James Taylor, an artist he said he's been a fan of since he was a teenager. Zac and James traded vocals on the poignant new ZBB ballad, 'Colder Weather,' then segued into James' classic, 'Sweet Baby James.' Capped by a standing ovation, the performance proved to be one of the night's most memorable.

Two-time ACM Entertainer of the Year Toby Keith, on acoustic guitar, played his new single, 'Somewhere Else,' complete with a horn section.

The Mandalay Bay casino showcased performances by Sugarland and New Artist nominees The Band Perry and Eric Church. Sugarland lead singer Jennifer's soaring vocals on 'Tonight' accented by powerfully long crescendos and her animated facial expressions, earned the duo another of the night's standing ovations.

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Getty Images

Always the entertainer, Eric Church got the crowd to their feet during his hit, 'Smoke a Little Smoke.' Clad in his signature baseball hat and sunglasses, Eric had the audience rocking along and surely made his mother happy when he mouthed "Hi Mom" to the TV screen. Appropriately, smoke engulfed the singer as the last note of the song was played.

Top New Artist winners, the Band Perry performed their breakout hit, 'If I Die Young.' Clad in white, Kimberly delivered her characteristically powerful vocals, accompanied by her brothers' spot-on harmonies.

Back at the MGM Grand Arena, Dierks Bentley gave viewers a backstage tour, and performed the new single, 'Am I the Only One.' Dierks' performance echoed the song's lyrics and proved he knows how have a good time, as he ran offstage, bounding up the stairs and into the bleachers to finish the song amid a group of enthusiastic fans.

Keith Urban was up next, showcasing his more sensitive side with the beautiful ballad, 'Without You.' The song's music video played behind Keith as he sang on a stage that was outfitted with a lamp on an end table, giving viewers the feeling of what it might be like to hang out at home with the singer.

ACM Entertainer of the Year Taylor Swift made a 'Mean' TV debut with her new single. With an old house for a backdrop, banjo-picking Taylor and her band stood on a makeshift front porch, dressed in vintage country clothes. With a distinct country-jam-band vibe, the band walked towards the edge of the stage, as mid-song the backdrop changed to city skyscrapers, with Taylor singing, "Someday I'll be living in a big ol' city."

Sara Evans showcased her chart-climbing hit, 'A Little Bit Stronger,' as light rain fell in the background. Fitting piano accentuated her emotional vocals and a standing ovation greeted the songbird, making her feel right back at home after a six-year hiatus between albums.

Martina McBride's brand-new single, 'Teenage Daughters,' demonstrated a new side to the powerhouse vocalist. Written from the singer's firsthand experience, the tune struck a familiar chord with the audience, as photos of moms and daughters displayed in the background were a fitting touch to the song, earning the mom of three daughters thunderous applause at the song's close.

After a heartwarming and humorous introduction by fiancé Blake Shelton, ACM Top Female Vocalist winner Miranda Lambert took the stage in a bright pink dress, accented by a pink guitar and pink microphone. 'Heart Like Mine' proved to be a stand-out performance from the triple-ACM winner.

Show hosts Blake and Reba McEntire pulled double duty, as both also performed brand-new songs on the broadcast. With catchy lyrics and impressive vocals, Blake's 'Honey Bee' and Reba's 'When Love Gets a Hold of You' both have 'future smash hit' written all over them.

Two ACM "firsts" followed -- rapping and Ronnie Dunn minus Kix Brooks. Jason Aldean's 'Dirt Road Anthem' impressed the country crowd with a taste of hip-hop. The country-rocker channeled his inner Eminem, leaving the audience roaring with approval. Ronnie Dunn made his solo ACM debut with the powerful ballad, 'Bleed Red,' showcasing his trademark emotional vocals and featuring soaring musical and string accompaniment.

The award for most meaningful performance of the night certainly goes to Darius Rucker and his 'Music From the Heart' collaboration. The song was written by Chris Young, Brett James and 25 developmentally-disabled young adults from the ACM Lifting Lives Music Camp, each who sang with Darius. As statistics about developmental disabilities were displayed in the background, the singer performed arm-in-arm with many of the adults and didn't leave the stage until he high-fived and gave hugs to each and every one of them.

At just three hours, the ACM Awards featured stand-out performances by some of country music's biggest stars and once-in-a-lifetime surprises. One can only wonder what 2012's ACM show will have in store!

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