CBS’ “Big Brother” was the top draw among young adults on the broadcast networks Sunday, but the net couldn’t keep all that many around for the debut of drama “Reckless” that followed. In its second week, meanwhile, ABC’s “Rising Star” declined by about 20% from what had been a modest premiere.

BET’s telecast of the “BET Awards” was expected to rule as the night’s No. 1 program in adults 18-49, based on Nielsen overnights, though it looks to be lower than last year when it did a 3.4/10 in 18-49 and 7.77 million viewers overall.

According to preliminary national estimates from Nielsen, CBS opened with the timeslot-leading “60 Minutes” (1.1/4 in 18-49, 8.4 million viewers overall) and “Big Brother” (1.8/6 in 18-49, 5.8 million viewers overall); unlike its Wednesday and Thursday premieres, which were both up slightly from their year-ago bows, Sunday’s installment came in a tick lower.

Sultry legal drama “Reckless” followed “Big Brother” with a weak 0.7/2 in 18-49 and 4.1 million viewers overall for its premiere, down from the 1.3 demo rating for last year’s established “Unforgettable” when it premiered in late July in the timeslot behind “Big Brother.” At least “Reckless” held steady on the half-hour in demos while adding about 100,000 total viewers.

And at 10, the summer premiere of “Unforgettable” did a 0.9/3 in 18-49, 6.1 million viewers overall), on par with the rating it did for its April return for a string of episodes left over from last season’s order. While still a soft demo number, the Poppy Montgomery drama scores points by managing to build on its lead-in by 0.2 in 18-49, by 0.3 in 25-54 and by about 2 million total viewers.

At ABC, “Rising Star” averaged a 1.2 rating/4 share in adults 18-49 and 4.7 million viewers overall from 9 to 11 p.m., down 20% in 18-49 from its premiere (1.5) but good enough for the 18-49 broadcast lead in the time period. On a positive note, it did build slightly on its soft “Wipeout” lead-in (1.0/4 in 18-49, 4.0 million viewers overall) and then grew in 18-49 from its first half-hour (1.1) to its fourth (1.3). Opening the night for ABC was a repeat “America’s Funniest Home Videos” (0.9/3 in 18-49, 4.6 million viewers overall).

NBC stunted from 9 to 11 p.m. for a second straight week, airing “Last Comic Standing” special “Last Comic Standing Room Only” (1.1/3 in 18-49, 3.4 million viewers overall) directly opposite ABC’s “Rising Star.” Though it fell well short of last week’s special “America’s Got Talent,” the NBC comedy special nearly did the same 18-49 rating as the ABC music competition. The Peacock kicked things off with a repeat “American Ninja Warrior” (0.7/3 in 18-49, 2.8 million viewers overall).

Fox aired repeats of animated comedies “American Dad” (0.7/3 in 18-49, 1.5 million viewers overall), “Bob’s Burgers” (0.7/3 in 18-49, 1.4 million viewers overall), “The Simpsons” at both 8 (0.9/3 in 18-49, 2.0 million viewers overall) and 8:30 (1.0/3 in 18-49, 2.4 million viewers overall), “Family Guy” (1.2/4 in 18-49, 2.6 million viewers overall) and “American Dad” (0.9/3 in 18-49, 2.3 million viewers overall).

Preliminary 18-49 averages for the night: ABC and CBS, 1.1/3; NBC and Fox, 0.9/3; Univision, 0.7/2; Telemundo, 0.4/1.

In total viewers: CBS, 6.1 million; ABC, 4.5 million; NBC, 3.1 million; Fox, 2.0 million; Univision, 1.9 million; Telemundo, 1.0 million.