The opening episode of the new X Factor USA series has endured its worst ratings yet.

The show - featuring new judges Kelly Rowland and Paulina Rubio - drew in 6.2 million viewers on Wednesday (September 13).

Its very first episode back in 2011 had an audience of 12.1 million people, however.

The Fox show on Wednesday was trumped by Big Brother, which had 6.7 million viewers.

Speaking on Twitter before its launch, Cowell said of the new US series: "Hello. The X factor USA starts tonight on fox. It's better. Funnier. And some of the contestants tonight are very special. Hope you like it."

However, its panel - which has lost Britney Spears and L.A. Reid from its last series - has been criticised for being uninteresting.