CBS’ “Big Brother” remained the night’s top draw among young adults Sunday, rising week to week despite special competition from an NFL preseason game on Fox. In total viewers, the reality competition hit a high for any of its 24 episodes this summer.

According to preliminary “live plus same-day” estimates from Nielsen, CBS opened Sunday with “60 Minutes” (0.9/3 in 18-49, 7.8 million viewers overall), the night’s most-watched program overall, followed by “Big Brother” (2.1/7 in 18-49, 6.9 million viewers overall), which again more than doubled the newsmag’s demo rating. “Big Brother”

From 9 to 11 p.m., “Unforgettable” (0.8/3 in 18-49, 6.2 million viewers overall) was steady with its most recent episode of two weeks ago and “Reckless” was down a tenth to its low (0.5/2 in 18-49, 4.4 million viewers overall). Despite the demo dip, “Reckless” continues to add viewers, and Sunday’s growth (about 120,000 from two weeks ago) means the show has increased its audience with each of its last five episodes (since its Week 2 low of 3.77 million).

Elsewhere, Fox’s NFL exhibition game between the Kansas City Chiefs and Carolina Panthers averaged a 2.0/6 in 18-49 and about 6 million viewers overall on the net’s stations from 8 to 11 p.m., with these numbers expected to rise in the vicinity of 10% in the nationals.

At ABC, an encore “America’s Funniest Home Videos” was the net’s top show of the night (1.0/4 in 18-49, 4.7 million viewers overall), outperforming originals of “Wipeout” (0.8/3 in 18-49, 3.0 million viewers overall) and “Rising Star” (0.8/2 in 18-49, 3.1 million viewers overall) and a repeat “Castle” (0.6/2 in 18-49, 3.8 million viewers overall). “Rising Star” was up a tenth in the demo from last week.

NBC aired two-hour repeats of “American Ninja Warrior” (0.7/2 in 18-49, 2.9 million viewers overall) and “America’s Got Talent” (0.8/3 in 18-49, 3.2 million viewers overall).

Preliminary 18-49 averages for the night: Fox, 1.8/6; CBS, 1.1/4; ABC, 0.8/3; NBC and Univision, 0.7/2; Telemundo, 0.4/1.

In total viewers: CBS, 6.3 million; Fox, 5.1 million; ABC, 3.7 million; NBC, 3.1 million; Univision, 1.9 million; Telemundo, 0.9 million.