Facing a night filled with reruns on competing networks, “American Idol” dominated primetime even more than usual, giving Fox the most- watched Thursday of any network since March 2007.

“Idol” (8.1 rating/23 share among adults 18-49, 25.0 million viewers

overall) improved more than 10% compared to its previous week, according to preliminary nationals from Nielsen. Combined, CBS, ABC, NBC and the CW averaged 17.5 million viewers.

CBS finished in second place among the English-language broadcast nets from 8-10 p.m., with “The Big Bang Theory” (2.5/8, 9.2 million), “Rules of Engagement” (2.3/7, 8.3 million) and “CSI” (1.8/5, 8.7 million). “Rules” represented the night’s only firstrun scripted program. Univision’s “Eva Luna” matched “CSI” in the demo.

After Fox signed off from its national programming, CBS then won at 10 p.m. with “The Mentalist” (1.9/5, 10.4 million).

ABC’s best performance of the night came at 8 p.m. with “Wipeout” (1.4/4, 5.0 million). The Alphabet net then slowly sank with repeats of “Grey’s Anatomy” (1.2/3, 4.0 million) and “Private Practice” (0.9/3, 3.1 million).

NBC’s night consisted of a sextet of “The Office” repeats, all generating between 1.2/4 and 1.6/4 in the demo and 2.7 million-3.2 million viewers overall. The comedy performed best in its usual 9 p.m. timeslot.

The CW trickled in with repeats of “The Vampire Diaries” (0.5/2, 1.3 million) and “Nikita” (0.4/1, 1.1 million.) Preliminary 18-49 averages for the night: Fox 8.1/23, CBS 2.0/6, Univision 1.6/5, NBC 1.4/4, ABC 1.2/3, CW 0.4/1.

In total viewers: Fox 25.0 million, CBS 9.3 million, ABC 4.0 million, Univision 3.9 million, NBC 3.0 million, CW 1.2 million.