The Simon Fuller/Nigel Lythgoe contest slipped to 6.5m (2.4) in its two-hour slot from 8pm, the latest overnight data indicates.
Dogs in the City, the night's only other original programme, slumped to 5.2m (0.9) on CBS between 8pm and 9pm.
Post-watershed repeats of Criminal Minds (5.9m/1.2) and CSI (6.4m/1.3) helped the Tiffany Network finish behind Fox in second place.
Betty White's Off Their Rockers (4.6m/1.1) kicked the night off on NBC, after which a double bill of Law & Order: SVU had 3.6m (0.8) and 4.2m (1.1) until 11pm.
The Middle (3.9m/1.0), Suburgatory (3.4m/0.9), Modern Family (4.3m/1.4) and Happy Endings (3m/1.1) gave ABC victory over NBC between 8pm and 10pm.