On tonight's (July 5) episode of 'Duets,' the superstars and amateurs were asked to sing standards -- classic songs that have stood the test of time. Sugarland singer (and expectant mother) Jennifer Nettles and her ace partner J. Rome offered up their rendition of Billie Holiday's 'God Bless the Child,' which was penned in 1939. How'd they do?

Well, Nettles chose this song since she wanted to show that Rome, long the favorite to take the competition, can do many things, from club bangers to jazzy, soulfly classics. It was important to prove that he's not a one note who can only sing contemporary songs. Mentor Kelly Clarkson, who has a hairline fracture in her foot, was so moved by J. Rome's perf that she stood up for him three times. Impressive, right?

Nettles and Rome turned in an awards show-style performance. That is, it felt like Rome already had an established career and was invited to sing with Nettles for a one-off at the Grammys. That's how pro he is already.

Mentor John Legend said it best when he commented, "You murdered it."

While we would expect J. Rome to own an Usher song, as opposed to a Billie Holiday song, he proved why he is the frontrunner to be the winner of Season 1 of 'Duets.'

Watch Jennifer Nettles + J. Rome Perform 'God Bless the Child' on 'Duets'