Korean sensations the Wonder Girls recently stopped by Billboard.com's offices to perform a cover B.o.B. and Bruno Mars' 'Nothin' on You' for the site's Mashup Mondays series. The song was chosen by popular fan vote.

The smash single was chosen by 47 percent of thousands of Wonder Girls fans who voted, beating out Miley Cyrus' 'Party in the U.S.A.' by just 43 percent. "We just want to express our love to our fans," says Sunye about the majority vote for 'Nothin' on You.' "It's a perfect song."

"The first thing was arranging the instruments," adds Yeeun. "I started practicing piano and then we added two more guitarists. And later a percussionist joined. And also we were traveling a lot, so we couldn't stay at one place. We had to practice on the street on the way."

The Wonder Girls opened for the Jonas Brothers in 2009, and trekked across the country on a headlining tour of their own in 2010. The South Korean pop stars, who have released two US singles -- 'Nobody' and '2 Different Tears' -- are set to release their debut American album this year.

Watch the Wonder Girls Cover B.o.B. and Bruno Mars' 'Nothin' on You'