A relative ratings surge for the opening-season finale of “The X Factor” pushed Fox to a primetime victory Thursday.

According to preliminary nationals from Nielsen, “X Factor” (3.8 rating/11 share in 18-49, 12.4 million viewers overall) improved more than 33% in its demo rating compared to the previous week and more than 20% in overall viewers. It was the program’s best-performing Thursday since Oct. 6 and Fox’s most-watched entertainment telecast since premiere week.

In its final halfhour, “X Factor” peaked at 4.2/12 in 18-49 and 13.8 million overall.

Airing repeats, CBS was second on the night among the networks, led by “The Big Bang Theory” (2.6/8, 9.1 million), followed by “Rules of Engagement” (1.9/6, 6.8 million), “Person of Interest” (1.6/5, 7.9 million) and “The Mentalist” (1.5/4, 8.2 million). CBS’ 18-49 rating declined during the final two hours even as its overall viewership rose.

Thanks to the latest edition of its stripped gameshow “Who’s Still Standing” (1.5/5, 5.2 million), NBC narrowly grabbed third-place honors. Repeats of “The Office” (0.9/2, 2.2 million) and “Whitney” (0.8/2, 1.9 million) preceded a burnoff episode of terminated drama “Prime Suspect” (1.0/3, 4.3 million).

ABC came in fourth with repeats of holiday specials “Prep and Landing” (1.1/3, 3.8 million), “Prep and Landing: Naughty vs. Nice” (1.1/3, 3.7 million) and “I Want a Dog for Christmas, Charlie Brown” (1.1/3, 3.6 million), followed by “Grey’s Anatomy” (0.7/2, 2.5 million).

The CW aired reruns of “The Vampire Diaries” (0.4/1, 1.4 million) and “The Secret Circle” (0.5/1, 1.4 million).

Univision made a dent at 9 p.m. with “La Fuerza del Destino” (1.8/5, 4.6 million), edging CBS for second place in the hour among viewers 18-49.

Preliminary 18-49 averages for the night: Fox 3.8/11, CBS 1.8/5, Univision 1.4/4, NBC 1.1/3, ABC 1.0/3, CW 0.5/1.

In total viewers: Fox 12.4 million, CBS 8.0 million, NBC 3.9 million, Univision 3.6 million, ABC 3.3 million, CW 1.7 million.