Diva alert! Jennifer Nettles -- who served as the host of the 2013 'CMA Country Christmas' on Monday (Dec. 2) -- sang many songs through the evening. But perhaps her most powerful moment was her absolutely gorgeous duet with soul singer Mary J. Blige, 'Do You Hear What I Hear?' 

Blige started the song, with Nettles taking the second verse. They met in the middle for the chorus, with their melodious voices mingling flawlessly.

Both songstresses are powerhouses with some seriously incredible range and they went vocal cord to vocal cord, matching each other note for note and lyric for lyric -- but it wasn't competitive. It was as though they were encouraging each other to let their voices soar so high that they reached the heavens. Performing together brought out the best in both of them.

Nettles and Blige sang the song while facing one another, losing themselves in the overall performance. It was a total immersion into a holy hymn. "Wow" is pretty much all we can say.