The country star and R&B singer rehearsed their rendition Thursday afternoon of Bill Withers "Ain't No Sunshine" inside the Nokia Theatre in downtown Los Angeles.
The pair, who has never performed together, spent most of their rehearsal time working out the kinks for a minimalist performance that features no band—just a cellist, Urban on guitar and Miguel broadcasting the rest of the song from his laptop.
"That's our whole band right there," said Urban, looking cool on stage in a T-shirt and jeans after removing his leather jacket at the beginning of the practice.
While Miguel, who won the Grammy for best R&B song earlier this year for "Adorn," tinkered with the tune on his computer at one point during the rehearsal, Urban and the backup cellist broke into an impromptu rendition of "Have Yourself a Merry Little Christmas" underneath the starry scene projected on screens above them.
"I don't have any of that on my laptop," joked Miguel.
After the duo finished their rehearsal, a giddy Lorde later took the stage to perform a pulsating, stripped-down version of her hit, "Royals." Dressed casually in a flowing white shirt, black jeans and purple lipstick, the breakout 17-year-old singer breezed through the song on her first attempt.
Other artists scheduled to appear at the nominations concert include Macklemore and Ryan Lewis, and Robin Thicke, who will team up with T.I. and Earth, Wind and Fire to perform "Blurred Lines." The show will also feature pre-taped performances from Katy Perry and Taylor Swift.
The 6-year-old nominations show returns to the Nokia Theatre after being held last year in Nashville, Tenn., at the Bridgestone Arena.
The 56th annual Grammy Awards will take place Jan. 26 across the street at the Staples Center.
Follow AP Entertainment Writer Derrik J. Lang on Twitter at http://www.twitter.com/derrikjlang