Fast National ratings for Tuesday, Jan. 13, 2009.

The eighth season of FOX's "American Idol" premiered to an audience of 30 million viewers on Tuesday night, down from last season but still a remarkable figure in this network TV landscape.

FOX averaged a whopping 11.6 rating in the key 18-49 demographic, beating the 3.5 rating for CBS and NBC's 3.3 rating. ABC's 2.3 rating was fourth, followed by the 0.8 rating for The CW.

Overall, FOX averaged a 15.8 rating/23 share for the night. CBS held up remarkably well against the "Idol" onslaught, doing a 10.2/16 for the night. NBC's 5.6/9 and ABC's 3.7/6 were next, with The CW's 1.2/2 in fifth.

The first hour of "American Idol" had a 14.5/22 in the 8 p.m. hour for FOX. CBS' "NCIS" was second with an 11.3/17. NBC's "Biggest Loser: Couples" was third with a 5.0/8, beating "Homeland Security USA" on ABC. "Idol" took a huge chunk out of the audience for "90210," which did only a 1.5/2 for The CW.

At 9 p.m. "Idol" was up to a 17.1/25. CBS again stayed steady with an 11.1/16 for "The Mentalist." NBC's "Biggest Loser" was third. "Idol" also bit into the audience for "Scrubs," which fell to a 2.8/4 in its second week on ABC. The CW's "Privileged" may be on life support after a 0.8/1. 

CBS moved into first at 10 p.m. with an 8.0/13 for "Without a Trace." NBC's "Law & Order: Special Victims Unit" was second with a 6.1/10. ABC's "What Would You Do?" special was third.

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