Alicia Keys Backing Singers Raii and Whitney Smith Impress on Americas Got Talent Watch

"My God, you can really sing," Simon Cowell said.

Backup vocalists Raii and Whitney Smith spend a lot of time on stage in the background for recording artists Alicia Keys, Emeli Sande and Estelle. On Tuesday night's (June 28) episode of America's Got Talent, the husband and wife team stepped into the spotlight and blew away the judges with an impressive performance of Marvin Gaye and Tammi Terrell's classic duet, "You're All I Need to Get By."

The duo first met  years ago as undergraduate students--Raii was attending the University of Illinois and Whitney attended Parkland College. The two hit it off  while both performing in a gospel group, and married in 2010. The two now live in New York, traveling the world singing backup while attempting to establish themselves as artists. The pair were both overcome by emotion as the audience-and judges-heaped praise about their audition.

"I have to say, you are both amazing singers, completely pitch perfect," said Mel. B.

Heidi Klum was charmed by the married couple's chemistry as well as their personal relationship. "I think you guys are a fantastic duo," she said. "I love that you're a married couple singing together."

Howie Mandel praised The Smiths' "throwback" vibe and potential for the future. "There's no question about your singing and style," he said. "There isn't anybody like you."

For a second, it seemed like Simon Cowell would be a holdout, but he leapt onboard. "You started quite normally and I thought this was a little bit karaoke," he said. "But in the middle you both let it rip and that's when I thought, "My God, you can really sing."

Cowell knows a thing or two about bringing backup singers into the foreground. While on American Idol, Cowell -- alongside judges Paula Abdul and Randy Jackson -- supported the journey of Melinda Doolittle, who began as a backup singer but forged through to finish third on Idol's sixth season.

America got a glimpse of The Smiths at the beginning of the year on Dick Clark's New Years Rockin' Eve with Ryan Seacrest as the two supported Wiz Khalifa and Charlie Puth for the hit, "See You Again," on Dec. 31. 

The duo hits the road for three dates with Estelle kicking off in New Orleans, Louisiana July 1. 

America's Got Talent airs 8 p.m. EST Tuesdays on NBC. The live shows kick off on July 26.

Watch their audition below: