The competition left an opening and CBS took full advantage Thursday, as its lineup — led by series highs for megahit “The Big Bang Theory” — dominated the night in all key demos.

It was a good night all around for CBS, which opted to bring back its Thursday regulars before the competition. In both adults 18-49 and total viewers, the Eye beat the combined deliveries of ABC, NBC and Fox.

According to preliminary national estimates from Nielsen, “The Big Bang Theory” matched its all-time same-night high in adults 18-49 (6.0 rating/17 share) while drawing its largest overall audience (19.0 million); it shot up by 11% over its most recent original on Dec. 13 (5.4). Also dominating its timeslot was “Two and a Half Men” (4.6/12 in 18-49, 15.4 million viewers overall), which was up 12% from its last original episode.

CBS also comfortably led its rivals from 9 to 11 p.m. with “Person of Interest” “(3.4/9 in 18-49, 16.1 million viewers overall) and “Elementary” (2.5/7 in 18-49, 11.4 million viewers overall), which were up 17% and 9%, respectively, vs. their last first-run airings. “Person” matched its series high in the demo and hit a high in total viewers, and “Elementary” posted its best numbers since its Sept. 27 premiere.

Fox was the only other broadcaster airing first-run programming, but its two “Mobbed” specials didn’t do much, averaging a 1.0/3 in 18-49 and 3.4 million viewers overall at 8 p.m. and a 1.2/3 in 18-49 and 2.7 million viewers overall at 9.

ABC aired a special repeat of Wednesday drama “Nashville” (0.7/2 in 18-49, 3.2 million viewers overall) followed by back-to-back encores of “Scandal” (0.7/2 in 18-49, 2.9 million viewers overall at 9 and 0.9/3 in 18-49, 3.7 million viewers overall in its regular slot at 10).

NBC went with encores of Thursday regulars “30 Rock” (0.8/2 in 18-49, 2.5 million viewers overall), “Up All Night” (0.8/2 in 18-49, 2.0 million viewers overall), “The Office” (0.9/2 in 18-49, 2.2 million viewers overall), “Parks and Recreation” (0.7/2 in 18-49, 1.7 million viewers overall) and “Rock Center with Brian Williams” (0.6/2 in 18-49, 1.7 million viewers overall).

And CW aired repeats of “The Vampire Diaries” (0.4/1 in 18-49, 1.1 million viewers overall) and “Beauty and the Beast” (0.3/1 in 18-49, 0.9 million viewers overall).

As it has several times over the last week, Univision ranked second among the broadcasters in adults 18-49 with its original novelas, led by “Amores Verdaderos” (1.8/5 in 18-49, 4.7 million viewers overall).

Preliminary 18-49 averages for the night: CBS, 3.7/10; Univision, 1.7/4; Fox, 1.1/3; ABC and NBC, 0.8/2; CW, 0.4/1.

In total viewers: CBS, 14.9 million; Univision, 4.2 million; ABC, 3.3 million; Fox, 2.9 million; NBC, 2.5 million; CW, 1.0 million.