NBC crushed the competition Sunday behind another big night of Olympics action and an hourlong Michael Phelps special. CBS’ ”Big Brother” wasn’t affected, actually rising week to week, but ABC’s feel-good reality shows tumbled.

According to preliminary national estimates from Nielsen, NBC’s ”Michael Phelps: America’s Golden Champion” averaged a 5.9 rating/20 share in adults 18-49 and 20.5 million viewers overall in the 7 o’clock hour. It was followed by the ninth night of competition at the London Games, which averaged a 10.5/27 in 18-49 and 32.1 million viewers overall from 8 to 11. While the primetime portion was down a bit from the opening Sunday of competition, it was up nicely vs. the comparable night in Beijing four years ago.

At CBS, ”60 Minutes” (1.0/3 in 18-49, 6.5 million viewers overall) was followed by ”Big Brother” (2.1/6 in 18-49, 5.8 million viewers overall), which grew 10% week to week and was the night’s top-rated broadcast series among adults 18-49. Audiences vanished thereafter, though, with repeats of ”Hawaii Five-0” (0.5/1 in 18-49, 2.9 million viewers overall) and ”The Mentalist” (0.6/2 in 18-49, 3.3 million viewers overall).

ABC opened with a repeat of ”America’s Funniest Home Videos” (0.9/3 in 18-49, 3.9 million viewers overall), which actually rated higher than the original episodes of ”Secret Millionaire” (0.8/2 in 18-439, 3.9 million viewers overall) Extreme Makeover: Weight Loss Edition” (0.7/2 in 18-49, 2.5 million viewers overall) that followed. After airing repeats against the first Sunday of the Olympics, the feel-good reality shows drew their lowest scores to date for original episodes.

Fox ranked second on the night in 18-49 behind encores of its animated comedies, starting with ”American Dad” (0.6/2 in 18-49, 1.6 million viewers overall) and ”The Cleveland Show” (0.8/2 in 18-49, 1.7 million viewers overall) and then an hour of ”The Simpsons” (1.3/4 in 18-49, 2.9 million viewers overall at 8 and 1.5/4 in 18-49, 3.3 million viewers overall at 8:30) and ”Family Guy” (1.5/4 in 18-49, 3.3 million viewers overall at 9 and 1.6/4 in 18-49, 3.4 million viewers overall at 9:30).

Preliminary 18-49 averages for the night: NBC, 9.3/26; Fox, 1.2/3; CBS, 1.1/3; Univision, 0.9/3; ABC, 0.8/3.

In total viewers: NBC, 29.2 million; CBS, 4.6 million; ABC, 3.2 million; Fox, 2.7 million; Univision, 1.4 million.