Rules of Engagement dropped 10% to a 2.7 adults rating and 9.71 million viewers at 8.30pm. The mid-season finale for Person of Interest climbed to its highest audience figure since its debut with 12.78m (2.7) at 9pm, while The Mentalist took in the most viewers on the night with 12.98m (2.7) at 10pm.
The X Factor semi-final slipped slightly to 9.65m (2.8) at 8pm for Fox. A repeat of Bones attracted 5.42m (1.5) at 9pm.
ABC's retrospective The Year with Katie Couric was watched by 5.52m (1.5) at 9pm, while a rerun of the classic Charlie Brown Christmas took in 6.41m (1.8) at 8pm.
NBC's only piece of new programming was Prime Suspect, which tumbled to a series low of 3.62m (0.8) at 10pm.