CBS comedy “The Big Bang Theory” debuted impressively on its new night Thursday, providing a substantial sampling opportunity for the net’s “Bleep My Dad Says,” which opened as the night’s top new show. Among the other rookies, ABC’s “My Generation” struggled in its bow, while NBC’s “Outsourced” did pretty well.

Meanwhile, the addition of CBS comedies in the night’s opening hour didn’t seem to hurt NBC, whose “Community” and “30 Rock” held up nicely, while 9 p.m. vet “The Office” remained potent and was up vs. last year. ABC’s “Grey’s Anatomy” returned strong to win the night’s middle hour in demos, and CBS’ “The Mentalist” carried the 10 o’clock hour in most categories (tying with ABC’s “Private Practice” in 18-49).

Overall, according to preliminary national estimates from Nielsen, CBS won in adults 18-49 (3.7/11) and total viewers (14.4 million), with ABC second in both (3.4/11, 9.4 million).

The Eye kicked off the night with a convincing victory for former Monday comedy “The Big Bang Theory” (4.8 rating/15 share in adults 18-49, 14.0 million viewers overall), which was up slightly over its opener of a year ago. It was followed by the debut of William Shatner half-hour “Bleep My Dad Says” (3.9/12 in 18-49, 12.5 million viewers overall), which retained 81% of its lead-in and stood as the night’s No. 4 show in 18-49.

Also for CBS, “CSI” (3.4/9 in 18-49, 14.6 million viewers overall) continues to show its age as it kicked off its 11th season with a third-place 18-49 finish at 9 o’clock but still led the hour in total viewers; and guest star Justin Bieber did boost viewership among teens (2.3/8), as the crime show led its hour and was up vs. last year among the Clearasil crowd. And “The Mentalist” (3.3/10 in 18-49, 15.3 million viewers overall) was down as well from last year (when it faced tougher competition from the second half of the “Grey’s Anatomy” premiere) but retained about all of its “CSI” demo lead-in while building on the vet in total viewers.

At NBC, “Community” (2.2/7 in 18-49, 5.0 million viewers overall) and “30 Rock” (2.6/8 in 18-49, 5.8 million viewers overall) were up over last year’s opening Thursday hour for NBC in premiere week. The net then surged at 9 o’clock with the first episode in the final season for Steve Carell on “The Office” (4.3/11 in 18-49, 8.4 million viewers overall), which ranked second in 18-49 in its slot, and new comedy “Outsourced” (3.5/9, 5.6 million viewers overall) retained about 80% of its lead-in at 9:30; NBC didn’t do better in the timeslot with anything other than “The Office” all of last season. “The Apprentice,” though, ended the night on a sour note for NBC (1.4/4 in 18-49, 3.8 million viewers overall).

ABC opened modestly as expected with new drama “My Generation” (1.6/5 in 18-49, 5.2 million viewers overall) but “Grey’s Anatomy” had a strong premiere (5.3/14 in 18-49, 14.0 million viewers overall), down roughly 20% from last year but logging what looks to be premiere week’s No. 2 score for a scripted series (behind Fox’s “Glee”) and generating the show’s best 18-49 score in the hour since November. “Private Practice” then kicked off its season with a 3.3/10 in 18-49 (tying “The Mentalist” and its best since February) while drawing 9 million viewers overall.

Fox’s combo of “Bones” (2.7/8 in 18-49, 9.8 million viewers overall) and “Fringe” (2.1/6 in 18-49, 5.8 million viewers overall) were off just a tad vs. their showing in premiere week a year ago (though both were down more vs. their season premieres of last year, which came earlier in September).

And despite the onslaught of premieres, CW’s “Vampire Diaries” remained strong (1.6/5 in 18-49, 3.6 million viewers overall), rising week to week in key demos, followed by “Nikita” (1.1/3 in 18-49, 3.2 million viewers overall), which stayed above 3 million viewers in its third outing.

Preliminary 18-49 averages for the night: CBS, 3.7/11; ABC, 3.4/10; NBC, 2.6/7; Fox, 2.4/7; Univision, 1.7/5; CW, 1.3/4.

In total viewers: CBS, 14.4 million; ABC, 9.4 million; Fox, 7.8 million; NBC, 5.7 million; Univision, 4.1 million; CW, 3.4 million.