Just...Damn.

This is a two year old clip. Something called "UK's The Voice" which I assume is a singing competition show. 

I have never watched. If they'd replace the competition format and just have Tom Jones and Jennifer Hudson belt out duets like this for an hour, I'd watch every week.

I used to sing for a living and know a thing or two about how the human voice works. Two things impress the hell out of me here, beyond the obvious.

First, they're both sitting down.  I know you see people sing sitting down sometimes, but how often do you see people belt out with power like this sitting down?  Rarely.  Sitting compresses your diaphragm and makes it tough to really lay into a song, particularly if you are singing a long string of notes with power.  

Second, they were judging a competition and this was apparently impromptu.  No warm up and they've never sung the song together.  I can tell you that warming up is pretty essential for a vocalist, particularly if you're going to hit the highs or lows of your range.  It also doesn't hurt to run through a duet before you do it for a live audience. 

Obviously, these two are exceptions to everything I know about singing.  They make it look effortless and I can tell you it is anything but. 

Just bloody incredible.