EXCLUSIVE: CBS has cut the order to veteran comedy Rules Of Engagement from 18 to 13 episodes. Rules was originally picked up for 18 episodes, with two leftover episodes from last season bringing the total order to 20 half-hours. (Rules, which wraps production December 6, will now air 15 episodes.) The long-running comedy was slated to air on Saturdays, but after freshman How To Be A Gentleman‘s underwhelming launch in the Thursday 8:30 PM slot, Rules was summoned in and took over the post-Big Bang Theory berth. It currently tops the 8:30-9 PM time period in total viewers with 11.6 million and averages a healthy 3.7 rating in 18-49, after setting highs in several categories this fall. With rookie 2 Broke Girls performing as well as it does along with all CBS returning comedies, the network needs an opening to launch its midseason comedy starring Rob Schneider, so a shorter, 15-episode run of Rules will provide a slot for the newbie. As for next season, given Rules‘ solid performance, the veteran has a good shot to return, especially if the Schneider series underperforms and/or CBS expands its comedy offerings to eight in two-hour comedy blocks on Mondays and Thursdays.