Fox didn’t have much competition in broadcast prime time Thursday night, with its rival networks dusting off plenty of repeat programming. With its two-hour “American Idol” running virtually unopposed, Fox coasted to a comfortable win for the night, based on Nielsen overnights.

TVbytheNumbers.com reports that “Idol” delivered a preliminary 3.8 average rating in the key 18-49 demo — continuing its pattern of erosion, but only a little. The show was down one-tenth of a point from last Thursday’s installment.

CBS’s all-repeat lineup came in second, easily beating mixes of repeat and fresh programs on ABC and NBC. Spanish-language Univision continued its competitive streak against English-language broadcasters with a third-place finish overall.

For the night, Fox led the way with a 3.8 average in viewers 18-49, followed by CBS (2.0 average), Univision (1.6), ABC (0.9) and NBC (0.9). Fox also led total viewers with 12.5 million to CBS’s 8.9 million, Univision’s 3.9 million, ABC’s 3.7 million and NBC’s 2.8 million.

ABC’s only non-repeat in prime was “Zero Hour,” which dipped one-tenth from last week to a 1.0 in 18-49.

NBC sprinkled its reruns with fresh episodes of “Community” (1.1 average in 18-49, tying last week’s series low) and “1600 Penn” (down one-tenth to a series-low 0.9).