Watch Alicia Keys, Maren Morris' Fiery 'Once' at Grammys

R&B singer, rising country star trade verses on emotional cut from Morris' 'Hero' album

Alicia Keys and Maren Morris teamed up for a rendition of Morris' country-soul ballad "Once" at the 2017 Grammys on Sunday.

Fifteen-time Grammy winner Alicia Keys and first-time nominee Maren Morris delivered a punchy, string-slathered performance of Morris' ballad "Once" at the Grammys on Sunday. The slow-burning country-soul cut first appeared on Morris' debut album, Hero, last year.

Morris and Keys performed against a domestic backdrop: large candle-stands, glowing chandeliers and tall, arched windows. After Morris sang the first verse of "Once," Keys sauntered onstage to deliver the second, and the two artists exploded together during the song's histrionic final verse. The string section shivered and swelled, helping to articulate the ballad's natural rise and fall. 

Morris and Keys have performed together before: In December, they teamed up for an episode of CMT Crossroads, which pairs a country performer with an artist from another genre. "We are both up for any challenge," Keys told Rolling Stone at the time. "Maren does her style and I do my style and they blend so well together.

"You don't hear a note and think, 'That's a rock note and I like it because it's a rock note,'" Keys added. "You don't care what note it is, you just want to feel it and feel great."

Keys is not up for any awards this year; her last album, Here, came out after the deadline for Grammy submissions in 2016. Morris took home the Best Country Solo Performance trophy on Sunday for "My Church."