With shows on competing networks still in repeats, NBC scored a ratings victory on Wednesday with originals, including best-yet numbers for first-year drama “Chicago Fire” — the top series of the night.

According to preliminary national estimates from Nielsen, NBC led among the Big Four in the 18-49 demo in each hour, starting with comedies “Whitney” (1.8/5 in 18-49, 5.0 million viewers overall) and “Guys With Kids” (1.7/5 in 18-49, 4.4 million viewers overall); the former scored its highest 18-49 rating since its Wednesday premiere about a year ago, and the latter set a regular-slot series high.

The Peacock also scored with Dick Wolf dramas “Law & Order: SVU” (2.1/5 in 18-49, 7.7 million viewers overall), which matched its highest rating of the past 13 months, and “Chicago Fire” (2.4/6 in 18-49, 8.4 million viewers overall), which shot up 26% from its most recent original to hit a series high.

Elsewhere, it was very slow going for Fox’s occasional special series “Mobbed,” which aired original episodes at both 8 (1.0/3 in 18-49, 3.2 million viewers overall) and 9 (1.1/3 in 18-49, 2.7 million viewers overall). “American Idol” returns to Wednesdays when it kicks off its 12th season in a couple of weeks.

ABC aired repeats of its original Wednesday programs “The Middle” (1.8/5 in 18-49, 6.6 million viewers overall), “The Neighbors” (1.3/3 in 18-49, 4.8 million viewers overall), “Modern Family” (2.1/5 in 18-49, 6.5 million viewers overall), “Suburgatory” (1.3/3 in 18-49, 4.2 million viewers overall) and “Nashville” (1.1/3 in 18-49, 3.9 million viewers overall), with the latter being a clips show.

CBS went with a pair of special repeats of Monday comedy “Mike & Molly” (1.3/4 in 18-49, 6.2 million viewers overall at 8 and 1.6/4 in 18-49, 6.7 million viewers overall at 8:30), followed by encores of regular Wednesday dramas “Criminal Minds” (1.6/4 in 18-49, 6.6 million viewers overall) and “CSI” (1.3/4 in 18-49, 6.2 million viewers overall).

CW aired repeats of “Arrow” (0.5/1 in 18-49, 2.1 million viewers overall) and “Supernatural” (0.4/1 in 18-49, 1.4 million viewers overall).

Univision ranked second on the night among young adults behind “Amores Verdaderos” (1.8/5 in 18-49, 4.4 million viewers overall) and “Por Ella Soy Eva” (1.7/5 in 18-49, 4.0 million viewers overall).

Preliminary 18-49 averages for the night: NBC, 2.1/6; Univision, 1.6/4; ABC and CBS, 1.5/4; Fox, 1.1/3; CW, 0.5/1.

In total viewers: NBC, 6.9 million; CBS, 6.4 million; ABC, 5.0 million; Univision, 4.0 million; Fox, 3.0 million; CW, 1.8 million.