Facing strong competition from NBC’s Beijing Olympics, CBS’s reality show “Greatest American Dog” fell to its lowest rating yet last night, its third week in its new Wednesday timeslot.

“Dog” averaged a 1.3 adults 18-49 rating, according to Nielsen overnights, off 13 percent from a 1.5 last week. CBS swapped “Dog” with “Big Brother” after the former’s ratings began to fall on Thursdays after a decent debut.

“Dog” likely lost some ground to the Games, which performs very well among the older adults who tend to dominate “Dog’s” audience.

The night was saturated with repeats as the other networks have avoided scheduling originals against the Games. The night’s only other original non-Olympic show, ABC’s “Primetime Crime,” averaged a 1.3 at 10 p.m.

Meanwhile, the Olympics continued to dominate the competition, though ratings were nowhere near the record level from the previous night, when the women’s gymnastics teams and Michael Phelps competed in finals.

NBC led the night among viewers 18-49 with a 9.1 average overnight rating and a 26 share. Univision was second at 1.6/5, CBS third at 1.4/4, ABC fourth at 1.3/4, Fox fifth at 1.0/3 and CW sixth at 0.4/1.

Ratings for NBC are approximate as fast nationals measure 8 to 11 p.m. timeslot data and not actual program data. The Olympics lasted well past 11 p.m.
 
At 8 p.m. NBC was first with a 7.1 for Olympics coverage, followed by Univision with a 1.8 for “Al Diablo con los Guapos.” CBS was third with a 1.3 for “Greatest American Dog,” Fox fourth with a 1.2 for a repeat of “Bones,” ABC fifth with a 1.1 for a “Wife Swap” rerun and CW sixth with a 0.4 for a repeat of “America’s Next Top Model.”
 
NBC finished first again at 9 p.m. with a 9.3 for more Olympics, while Univision held onto second place with a 1.8 for “Fuego en la Sangre.” CBS was third with a 1.4 for a “Criminal Minds” rerun, ABC fourth with a 1.3 for a repeat of “Supernanny,” Fox fifth with a 0.8 for a repeat of “Terminator: The Sarah Connor Chronicles” and CW sixth with a rerun of “The Pussycat Dolls Present: Girlicious.”
 
At 10 p.m. NBC extended its lead with a 10.7 for the Olympics, while Univision, ABC and CBS all tied for second at 1.3, Univision for “Don Francisco Presenta,” ABC for “Primetime” and CBS for a repeat of “CSI: NY.”
 
Among households, NBC was first for the night with a 16.5 average overnight rating and a 27 share. CBS was second at 3.9/6, ABC third at 2.7/5, Fox fourth at 2.4/4, Univision fifth at 2.1/3 and CW sixth at 0.7/1.