NBC has continued its momentum into the new year as its “The Biggest Loser” returned strong Sunday and won its two-hour block in demos. Fox had a good night too as NFL action led into big scores for its animated comedies.

According to preliminary national estimates from Nielsen, “The Biggest Loser” averaged a 2.9 rating/7 share in adults 18-49 and 7.0 million viewers overall from 9 to 11 p.m., rising 21% above its season premiere of a year ago (on a Tuesday) and winning its time period in adults 18-49 and adults 25-54 (3.3/7). No episode of “Loser” has rated higher since the finale of its couples edition in May 2011.

The weight loss series moves to its regular timeslot tonight.

Opening the night for NBC, whose “Sunday Night Football” wrapped its season a week ago, was a two-hour “Dateline” (1.5/4 in 18-49, 5.9 million viewers overall), which was up 20% from its year-ago Sunday premiere.

Elsewhere, Fox won the night in demos as well as total viewers, with the conclusion of the wild-card NFL playoff game between the Seattle Seahawks and Washington Redskins averaging an estimated audience of more than 35 million in the 7 o’clock half-hour. Following the post-game show in the 7:30 p.m. half-hour, “The Simpsons” followed with a dominant showing at 8 (4.4/11 in 18-49, 9.6 million viewers overall), and “Bob’s Burgers” (3.1/8 in 18-49, 6.5 million viewers overall), “Family Guy” (3.5/8 in 18-49, 7.1 million viewers overall) and “American Dad” (2.8/7 in 18-49, 5.6 million viewers overall) were all well above average.

Compared to their most recent originals, “The Simpsons” was up by about 30%, while the other Fox comedies surged by 40% or more. For “Bob’s Burgers,” this was its best scores since the show’s series premiere two years ago.

At ABC, an encore “Once Upon a Time” (0.9/2 in 18-49, 3.4 million viewers overall) led into the first winter episode of “Once Upon a Time” (3.1/8 in 18-49, 9.0 million viewers overall), which was in line with its most recent original five weeks ago. “Revenge” (2.3/5 in 18-49, 7.0 million viewers overall) was also on par with its last original, but saw a rather alarming drop at the halfway point (going from a 2.5 at 9 to a 2.1 at 9:30). And the net’s experiment with original episodes of comedy in the 10 o’clock hour bombed, with “Happy Endings” (1.0/3 in 18-49, 2.6 million viewers overall) and “Don’t Trust the B in Apt. 23” (0.9/2 in 18-49, 2.2 million viewers overall) barely registering.

CBS opened with “60 Minutes” (1.4/4 in 18-49, 9.5 million viewers overall), which was the hour’s top non-sports choice in most categories, followed by a special repeat of “Person of Interest” (1.3/3 in 18-49, 8.4 million viewers overall). And from there, “The Good Wife” (1.8/4 in 18-49, 10.0 million viewers overall) and “The Mentalist” (2.1/6 in 18-49, 10.7 million viewers overall) kicked off the new year on the high end of their ratings range for the season.

Preliminary 18-49 averages for the night: Fox, 5.6/14; NBC, 2.2/6; ABC, 1.8/5; CBS, 1.7/4; Univision, 0.7/2.

In total viewers: Fox, 13.7 million; CBS, 9.7 million; NBC, 6.4 million; ABC, 5.5 million; Univision, 2.1 million.