Kelly Clarkson isn't known for having the subtlest of instruments. So I did wonder how she would handle the call when asked to sing the part of Christine in a Phantom of the Opera duet with Josh Groban.
The result wasn't a clean vocal, with dirt and edge prevalent throughout. This was a case of Kelly adapting the piece to fit her own style, rather than trying to imitate a Broadway singer. Let's be honest, purists of the show aren't going to be happy with it, what with it lacking purity of tone and much of it being tackled in chest voice. However, those familiar with Kelly will most likely be impressed by her management of dynamics and the demonstration of versatility in tone and timbre.
Also, keep in mind when watching, this was recorded very close to the Diva being ordered to cancel her current tour and rest her voice. So she most likely wasn't in the best of vocal health from the get-go.