Ester hit those notes in autotune. Anyone could sing on this track, really, it's all about the chemistry and sexiness that Usher and whoever can exude together.
But since Ciara is suppose to be on the final version, I tried to imagine her on it.... and I can't. To me it sounds good the way it is with Ester Dean on it but I can't judge anything until I heard Ciara on it, if we get to hear Ciara on it....