Fox topped the other major broadcast networks combined in key demos Tuesday night, as “American Idol” and “House” scored convincing victories once again.

According to preliminary nationals from Nielsen, “American Idol” (11.7 rating/33 share in adults 18-49, 29 million viewers overall) crushed the competition at 8, and “House” (8.4/21 in 18-49, 21.1 million viewers overall) did the same at 9 although it was off a bit from its monster series-high delivery of one week ago.

ABC’s conclusion of two-part original movie “The Ten Commandments” (3.9/10 in 18-49, 12 million viewers overall) was off from its solid Monday premiere but still delivered the net’s best showing from 9 to 11 on the night in months.

CBS was paced by a second-place perf at 9 by “The Unit” (3.8/9 in 18-49, 13.9 million viewers overall), which was down week to week but built nicely on its lead-in from a repeat “NCIS” (2.3/7 in 18-49, 11.3 million viewers overall).

NBC’s quiet night included fourth-place comedy showings from “Scrubs” (2.7/7 in 18-49 and 5.8 million viewers overall) and “Teachers” (2.4/6 in 18-49, 5.0 million viewers overall) and a third-place finish at 10 for a special episode of rookie Friday drama “Conviction” (2.5/7 in 18-49, 7.4 million viewers overall).

Preliminary 18-49 averages for the night: Fox, 10.0/27; CBS, 3.3/9; ABC, 3.2/8; NBC, 2.2/6; WB, 1.3/3; UPN, 0.9/2.

In total viewers: Fox, 25.0 million; CBS, 12.5 million; ABC, 9.8 million; NBC, 5.7 million; WB, 3.2 million; UPN, 2.1 million.