A new night did little to help NBC’s struggling new comedy “30 Rock.”

In its supersized Thursday premiere last night, and with the benefit of a decent “Office” lead-in, “Rock” averaged a disappointing 2.3 adults 18-49 average, according to Nielsen overnights. Final ratings may vary slightly, as fast nationals measure timeslot and not actual program data, and "Rock" bled through several timeslots.

The show, which aired from 9:20 to 10:01 p.m., lost nearly half of “The Office’s” 4.3, and drew only 5 million total viewers.

Granted, it aired against some of the toughest competition on television in ABC’s “Grey’s Anatomy” and CBS’s “CSI,” both of which were up from the previous week.

But “Rock” was below NBC’s modest 3.8 average for “Deal or No Deal” in the 9:30 timeslot last week. And it was slightly below the show’s season-to-date 2.4 average for four episodes in the Wednesday 8 p.m. timeslot.

Yet NBC probably won’t write off “Rock” just yet. In addition to being written, created by and starring network golden girl Tina Fey, the show still hasn’t aired with its new Thursday lead-in.

NBC will premiere “Scrubs” on Nov. 30 at 9 p.m., pairing the dryly humored sitcom with the similarly biting “Rock.” If “Rock” can’t improve then, it may be gone by Christmas.

Meanwhile, thanks to a strong “CSI,” CBS tied ABC for the first time this season among adults 18-49 on a Thursday night, despite the improved performance of ABC’s Barbara Walters special in the 10 p.m. timeslot, temporarily taking the place of yanked drama “Six Degrees.”

ABC and CBS each had a 5.9 average rating and a 15 share. NBC was third at 4.2/11, Fox fourth at 1.8/5, the CW fifth at 1.7/4 and Univision sixth at 1.6/4.
 
CBS began the night in the lead with a 5.4 average during the 8 p.m. hour for “Survivor.” NBC was second with a 4.0 for “My Name is Earl” and the first half of “The Office,” ABC third with a 3.9 for “Ugly Betty,” and Univision and CW tied for fourth at 2.0, Univision for “La Fea Mas Bella” and CW for “Smallville.” That left Fox sixth that hour with a 1.9 for “’Til Death,” which many speculate will move to Sunday in the coming weeks.
 
ABC took the lead at 9 p.m. with an 8.8 average for “Grey’s Anatomy,” the night’s top-rated show in the demo, 4 percent better than last week. CBS came in second that hour with a 7.9 for “CSI,” up 16 percent over last week, with NBC third with a 3.0 for the last 20 minutes of “Office” and a 40-minute “30 Rock,” Fox fourth with a 1.7 for “The O.C.,” Univision fifth with a 1.5 for “Mundo de Fieras” and CW sixth with a 1.3 for “Supernatural.”
 
NBC took its turn in the lead during the 10 p.m. hour with a 5.5 average for “ER.” ABC was second with a 4.9 for the Walters special “30 Mistakes in 30 Years,” CBS third with a 4.4 for “Shark” and Univision fourth with a 1.3 for “Aqui y Ahora.”
 
Among households, CBS finished the night on top with an 11.3 average rating and an 18 share. ABC was second at 10.5/16, NBC third at 5.9/9, Fox fourth at 2.7/4, CW fifth at 2.5/4 and Univision sixth at 2.0/3.