Fox’s ”American Idol” again dominated its Wednesday hour in key demos but with numbers that are down roughly 33% from the comparable night a year ago. The net’s ”Mobbed” also won its hour, while NBC’s comedies posted gains earlier in the evening.

According to preliminary national estimates from Nielsen, the sixth auditions episode of the season for ”American Idol” averaged a 5.9 rating/17 share in adults 18-49 and 18.2 million viewers overall, beating its combined ABC-CBS-NBC competition in the night’s opening hour among both adults 18-49 and total viewers. Still, ”Idol” was down about 8% week to week and off a big 33% from last year’s 9.0 demo score and 25 million viewers overall. It was followed by alternative series ”Mobbed” (2.9/7 in 18-49, 7.9 million viewers overall), which led its hour among young adults and more than doubled the averages for its previous episode when it didn’t air behind ”Idol.”

CBS opened with the annual special ”Super Bowl’s Greatest Commercials” (2.1/6 in 18-49, 8.7 million viewers overall), placing second in its 8 o’clock hour, and followed it up with repeats of ”Criminal Minds” (2.1/5 in 18-49, 8.2 million viewers overall) and ”CSI” (1.5/4 in 18-49, 7.4 million viewers overall), both of which led their hours in total viewers.

At NBC, ”Whitney” (1.7/5 in 18-49, 4.4 million viewers overall) and ”Are You There, Chelsea” (1.7/5 in 18-49, 4.1 million viewers overall) rebounded by about 20% from last week’s lows, moving ahead in demos over ABC’s repeat comedies after merely tying them seven days earlier. They were followed by a special repeat of ”Law and Order: Special Victims Unit” (1.1/3 in 18-49, 4.8 million viewers overall) and then another encore in the show’s regular timeslot (1.6/4 in 18-49, 5.8 million viewers overall). Next week, newsmag ”Rock Center” joins the lineup in the 9 o’clock hour.

ABC aired repeats of its regular Wednesday lineup: ”The Middle” (1.2/4 in 18-49, 4.9 million viewers overall), ”Suburgatory” (1.2/3 in 18-49, 4.2 million viewers overall), ”Modern Family” (2.7/7 in 18-49, 7.7 million viewers overall), ”Happy Endings” (1.9/5 in 18-49, 5.2 million viewers overall) and ”Revenge” (0.9/2 in 18-49, 3.3 million viewers overall).

And CW’s ”One Tree Hill” (0.7/2 in 18-49, 1.5 million viewers overall) and ”Remodeled” (0.3/1 in 18-49, 0.7 million viewers overall) were up slightly week to week.

Preliminary 18-49 averages for the night: Fox, 4.4/12; CBS, 1.9/5; ABC, NBC and Univision, 1.5/4; CW, 0.5/1.

In total viewers: Fox, 13.1 million; CBS, 8.1 million; NBC, 5.0 million; ABC, 4.8 million; Univision, 3.5 million; CW, 1.1 million.