CBS and Fox battled to a tie Thursday night in the coveted 18-49 demo, as CBS’s “Big Bang Theory” continued to beat Fox’s “American Idol” at 8 p.m., TVbytheNumbers.com reports, citing Nielsen overnights.

Both networks averaged 3.6 ratings in 18-49 for prime time, leaving the competition in the dust. NBC came in a distant third with a 1.8 average, followed by Univision and ABC, both at 1.4.

CBS had the edge in total viewers with 14.5 million to 12.1 million for Fox, well ahead of ABC (4.2 million), NBC (4.0 million) and Univision (3.5 million).

“Big Bang Theory” averaged a 5.1 rating in viewers 18-49 at 8 p.m., down two-tenths from its original episode two weeks ago but good enough to beat “Idol’s” 4.8 average for the one-hour installment, which was down 11% from last week’s two-hour “Idol.” “American Idol” did top “Bang” in total viewers, 16.98 million to 15.22 million.

NBC’s big news came at 10 p.m., and the news was bad: The new show “Awake” was down 20% from the show’s premiere a week earlier with a weak 1.6 average in 18-49, getting pounded by CBS’s “The Mentalist” with a 2.8 — up two-tenths from its previous original.

Elsewhere on NBC, “30 Rock” had its now typical 1.4 rating against tough competition at 8 p.m. from “Big Bang” and “Idol,” but “Parks & Recreation” (1.9 average), “The Office” (2.6) and “Up All Night” (1.7) were all up.

ABC took the night off, airing all repeats.