“House” aired its first new episode since “American Idol’s” debut two weeks ago last night, and the combination of the two shows proved dominant for Fox.

“Idol” averaged an 11.0 adults 18-49 rating at 8 p.m., according to Nielsen overnights, and “House” posted a season-high 8.6. Together, the two averaged a 9.8 rating on the night, 31 percent ahead of the 7.5 average for the other Big Five networks combined.

Still, while dominant, “Idol” and “House” were off 20 percent from the same week last year, when they combined for a 12.3 rating.

“Idol” has seen similar losses since returning for season seven two weeks ago, though it continues to be by far the highest-rated series on broadcast. Many other hit shows are seeing similar declines this year, with the percentage of DVR households in Nielsen’s sample more than doubled compared with last year.

“House” just missed becoming the season’s highest-rated episode for a scripted series, trailing the season premiere of ABC’s “Grey’s Anatomy” by 0.3. The medical drama has a special episode airing after the game Sunday, which should draw huge ratings.

Fox was first for the night among viewers 18-49 with a 9.8 average overnight rating and a 24 share. NBC was second at 3.2/8, CBS third at 2.0/5, Univision fourth at 1.7/4, ABC fifth at 1.4/4 and CW sixth at 0.9/2.
 
At 8 p.m. Fox was first with an 11.0 rating for “Idol,” with NBC second with a 2.7 for the first hour of “The Biggest Loser.” Univision and CBS tied for third at 2.0, Univision for “Al Diablo con los Guapos” and CBS for a repeat of “NCIS,” with ABC fifth with a 1.4 for an hour of “Just for Laughs” repeats and CW sixth with a 0.6 for a “Reaper” rerun.
 
Fox led again at 9 p.m. with an 8.6 for “House,” followed by NBC with a 4.0 for the second half of “Loser.” ABC was third with a 1.7 average for “According to Jim” (2.0) and “Carpoolers” (1.3), Univision fourth with a 1.6 for “Pasion,” CBS fifth with a 1.5 for a repeat of “The Unit” and CW sixth with a 1.3 for “One Tree Hill.”
 
At 10 p.m. NBC moved to first place with a 2.9 for a repeat of “Law & Order: Special Victims Unit,” while CBS took second with a 2.4 for “48 Hours Mystery.” Univision and ABC tied for third at 1.3, Univision for “Aqui y Ahora” and ABC for a repeat of “Boston Legal.”
 
Among households, Fox led the night with a 14.3 average overnight rating and a 21 share. CBS was second at 6.0/9, NBC third at 5.7/9, ABC fourth at 3.3/5, Univision fifth at 1.7/4 and CW sixth at 1.5/2.