Meghan Trainor & John Legend Perform 'Like I'm Gonna Lose You' at the 2015 Billboard Music Awards: Watch

Ethan Miller/Getty Images
John Legend and Meghan Trainor perform during the 2015 Billboard Music Awards at MGM Grand Garden Arena on May 17, 2015 in Las Vegas, Nevada. 

Meghan Trainor and John Legend have been winning over hearts with their individual Billboard No. 1 hits (respectively "All About the Bass" and "All of Me"), but at the 2015 Billboard Music Awards, they turned up the swoon with a live debut of their duet, "Like I'm Gonna Lose You."

Billboard Music Awards

Both singers took the stage on Sunday, May 17 to perform Trainor's latest Title single. She kicked off the performance by flexing her vocal prowess, before Legend stepped out to sing along, side by side.

"I'm a little jealous," Chrissy Tiegen, BBMA co-host and Legend's wife, joked after the duet.

The sweet ballad is Trainor's third single off heir debut album, Title, following "All About That Bass" and "Lips Are Movin'."

Billboard Music Awards 2015