Their voices randomly go together very well... if (when
) Luke does make it as an act in his own right, I wouldn't be surprised to see them release a one-off duet single.
Nicole and Sam... ... Nicole is clearly miles out of Sam's league as a "power singer" and she deliberately completely dominated that song. I forget that Sam was even on the stage. Although when I say "deliberately" - I think it's more that she can't help herself... it's not in her nature to step back and let someone else take the limelight (just look at her in Pussycat Dolls, or even on the judging panel). She's a show-off. But then, you don't get to be where Nicole Sherzinger is without being a show-off, so I guess that's to be expected.