• by Wayne Friedman , January 14, 2009

Fox's "American Idol" is back with big audiences--but not as big as a year ago. For the second year in a row, the "Idol" premiere witnessed another double-digit drop--this one 15% in key viewership in its 2009 premiere episode versus its 2008 edition. The show is now in its eighth season.

"Idol" grabbed a Nielsen preliminary 11.8 rating/28 share among advertisers' key 18-49 viewers Tuesday, with an average of 30 million overall viewers on the special two-hour episode. A year ago, its numbers were 13.8/32 for 18-49 and 33 million viewers. This year's premiere peaked in its second hour, earning a 13.1/29 in 18-49 viewers, with 32.7 million total viewers.

This is good news for CBS, which threw some of its better-performing dramas against "Idol" with "NCIS," "The Mentalist" and "Without a Trace." The network's numbers were up versus a week before--although CBS came in at a distant second place to Fox with a 3.5/8.

"NCIS" and "The Mentalist"--while down versus their respective season highs--both earned respectable numbers, at 3.8/9. "Trace" took in a 2.9/7 at 10 p.m., which tied for second place in the time period with ABC's "Primetime: What Would You Do?"

NBC moved lower week-to-week, down 20% in the 18-49 demos over the week before. "Biggest Loser" posted a 2.9/7 in its first hour and a 3.7/8 in its second hour. At 10 p.m., NBC won the time period as "Law & Order: SVU" grabbed a 3.6/9.

ABC's "Scrubs"--which had a decent premiere a week ago with a 3.2/8--went 30% lower against the big "Idol" train, earning a 2.2/5 at 9 p.m. Similarly, its 8 p.m. show, "Homeland Security USA," registered 15% less than its premiere a week ago, to a 1.9/5. ABC averaged a 2.3/6 for the night.

"Idol" also hit CW and its younger viewers. "90210" dropped to a 1.4/4 from a 1.8/5 among 18-34 viewers, with "Privileged" moving south to a 0.7/2 from a 1.1/3. Against the older viewer group of 18-49 viewers, "90210" dropped to a 1.1/3 from a 1.4/4, with "Privileged" rising to a 0.5/1 from a 0.8/2. CW ended up with a 0.8/2 for Tuesday among 18-49 viewers, and a 1.1/3 for its younger 18-34 viewers.

Against "Idol," Univision earned a respectable 1.7/4 among 18-49 viewers and a 1.9/5 among the 18-34 crowd--the exact numbers that the network averaged on Monday night for "Cuidado con el Angel," "Fuego en la Sangre" and "Aqui y Ahora."