Watch: Leona Lewis performs on 'X Factor USA' Finale...

The problem with being a global one hit wonder is that sometimes an artist doesn't know when to stop milking their breakthrough hit. Sure, it's often compulsory to perform your biggest hits on tour. But on X Factor USA? Well, I suppose it IS the Finale. And hopefully the last one we see from this failing series. Check out Leona Lewis performing 'One More Sleep', as well as 'Bleeding Love' with winners Alex & Sierra, inside.

Thoughts?