During Tuesday night's brand-new episode of "Glee," McKinley High School power couples old and new went toe-to-toe in a battle of duets. But only one pair emerged a clear winner. While their cohorts opted for show tunes and Muzak, burgeoning lovebirds Quinn (Dianna Agron) and Sam (newcomer Chord Overstreet) shined with their take on the adorable pop rock tune (not to mention inevitable prom and wedding staple) "Lucky."

Released on Jason Mraz's 2008 album We Sing. We Dance. We Steal Things, the singer-songwriter's duet with fellow mellow crooner Colbie Caillat became a beloved, bubbly hit that just begs you to sing along (its catchy chorus goes, "I'm lucky I'm in love with my best friend/ Lucky to have been where I have been/ Lucky to be coming home again.")

The song, which hit the airwaves in January 2009 and was certified gold by the RIAA on March 12, 2009, peaked at #9 on the Billboard Hot Adult Top 40 and reached #48 on the Hot 100 (it didn't come close to Mraz's other single from the album, "I'm Yours," which landed at #1 on the Hot 100). Still, "Lucky", became just that at the 2010 Grammy Awards as it emerged the winner of Best Pop Collaboration With Vocals. Interestingly enough, the song beat out Caillat's other duet that year, her collaboration with Taylor Swift on "Breathe."

So, how, exactly, did the sweet track come to be? The way so many unions have: on MySpace. Turns out, Mr. A-Z discovered Ms. Caillat's music via her MySpace page and wanted to work with her. Caillat explained to MTV Asian News that Mraz contacted her via e-mail hoping to collaborate, and that's just what they did. And in a most 21st-century fashion, the artists (along with Timothy Fagan) wrote the song through e-mails. While Mraz was recording We Sing. We Dance. We Steal Things, Caillat, who was in town promoting her own record, popped by the studio and laid down the track with him.

While it was a meant-to-be union from the get-go (sorry, hopeless romantics: Mraz and Caillat seem to keep things strictly professional), there were outside forces that could have kept them apart. After their Grammy win, Mraz divulged to Billboard that "Lucky" was "completely underground, because neither of our labels were into the idea." Fans were into it, however, as the song was also nominated for the People's Choice Award for Favorite Music Collaboration and a Teen Choice Award for Choice Music: Hook Up.

Other than performing their song together on "Saturday Night Live" and "The Ellen DeGeneres Show," Mraz and Caillat have not joined forces since their duet, though they have both since collaborated with other artists. Mexican singer Ximena Sariñana, helped Mraz with the Latin American and Spanish version of "Lucky" ("Suerte"), and both Ingrid Michaelson and Lisa Hannigan have filled in on Caillat's part for Mraz's tour. Caillat got unplugged once again when she performed an acoustic version of "The Light" with Common, featuring Zac Brown.