Fast National ratings for Thursday, October 20, 2011.

Viewers interest in the Cardinals-Rangers World Series remained steady from Game 1 to Game 2, giving FOX another nightly win in the Nielsens, while CBS got good results from swapping "Rules of Engagement" in for the canceled "How to Be a Gentleman," and NBC discovered that the only way to look worse with its Thursday numbers is to go with an all-repeat lineup, which for the night averaged lower than the CW in adults 18-49.

For the night, FOX averaged a 3.7 rating in the 18-49 demographic and 12.9 million viewers overall, followed by CBS (3.2, 12.6 million), ABC (2.4, 7.2 million), the CW (1.1, 2.5 million) and NBC (1.0, 2.7 million).

8 p.m. -- CBS won the hour handily, thanks to "The Big Bang Theory" (4.9, 14.7 million) and "Rules" (3.7, 11.5 million). In its last Thursday airing, "Gentleman" retained only 56% of the "Big Bang" lead-in, where "Rules' retained the perfectly-acceptable 75%. (Its numbers were roughly on par with the "Big Bang" repeat CBS aired here last week.) The World Series was second for the hour (3.0, 11.4 million), followed by "The Vampire Diaries" (1.3, 2.9 million), ABC's playing-out-the-string "Charlie's Angels" (1.2, 5.6 million) and NBC's repeat combo of "Community" and "Parks and Recreation" (1.0, 2.5 million).

9 p.m. --
The World Series led the way (3.8, 13.1 million), followed by ABC's "Grey's Anatomy" (3.5, 9.4 million), CBS' "Person of Interest" (2.7, 12.3 million, and inching towards a full-season pick-up at this point), NBC's "The Office"/"Whitney" repeats (1.3, 2.9 million) and the CW's "Secret Circle" (0.9, 2.1 million).

10 p.m. -- As the game remained close, interest in Game 2 only built, with a 4.4 demo rating and 14.2 million viewers for the hour. It was followed by CBS '"The Mentalist" (2.4, 12.5 million), ABC's "Private Practice" (2.4, 6.6 million) and a "Prime Suspect" repeat on NBC (0.8, 2.8 million).

All ratings information comes from preliminary Fast National Nielsen data, which includes live and same-day DVR viewing. All numbers are subject to change.