Brian Williams, Jon Stewart

NBC kept ratings expectations low for Rock Center with Brian Williams — and met them. Well, maybe they surpassed them a little bit. The newsmagazine's debut piqued the curiosity of 4.13 million people, posting a 1.0 rating in the 18-to-49 demo, Nielsen's fast overnights show.

"I know we're going to get crushed," Brian Williams said on MSNBC last week, toeing the party line uttered by NBC News President Steve Capus. The first show also was tepidly reviewed.

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The Monday at 10/9c time slot has been a black hole for NBC in the first seven weeks of the 2011-12 TV season. The Playboy Club tanked in just three weeks, getting 3.39 million and a 1.2 in the demo for its last airing; it was replaced by reruns of Prime Suspect (which, for what it's worth, snagged 2.50 million with a 0.7 rating last week).

For the seventh straight week of the new season, Castle nabbed the most viewers in the final hour of Monday's prime time — 12.94 million vs. 10.28 million for CBS' Hawaii Five-0. In the demo battle, they tied at 2.9.

Read our Dancing with the Stars recap

A 90-minute Dancing with the Stars, starting at 8:30/7:30c on ABC, averaged 16.28 million fans and 2.8 demo rating. NBC's The Sing-Off pulled in 4.39 million (1.4) over two hours.

CBS' comedy block had its usual solid showing: How I Met Your Mother (10.70 million/4.1 demo rating); 2 Broke Girls (11.14 million/4.2); Two and a Half Men (13.81 million/4.7)); and Mike & Molly (11.53 million/3.8). But with folks out trick-or-treating for Halloween, just about every show except Castle was down. Scared Shrekless, which aired for the first time last year on NBC, attracted 8.68 million viewers (1.7) on ABC.

Back-to-back reruns of The CW's Ringer averaged 941,000 (0.3).