CBS drama vet “NCIS” is flexing its muscles early in the new year, drawing its second largest overall audience ever for a second straight week as the Eye took the night in key demos. Fox’s “New Girl” was the top comedy among young adults in the night’s three-way faceoff.

According to preliminary national estimates from Nielsen, “NCIS” averaged a whopping 22.3 million viewers while ruling as the night’s top show in adults 18-49 (3.8/11) and 25-54 (5.8/14); this was the show’s second best 18-49 score of the season, its season high in 25-54 and its second largest overall audience ever (behind a February 2011 episode). The drama seems to be taking advantage of lesser competition in the timeslot, including the absence of NBC’s “The Voice,” which won’t return until late March.

Following “NCIS,” the Eye stayed on top with “NCIS: Los Angeles” (2.7/7 in 18-49, 17.5 million viewers overall), though it was down about 10% week to week and this was one of its weaker retentions of the original’s lead-in. And closing the night, “Vegas” held steady (1.6/4 in 18-49, 11.1 million viewers overall), placing second among the major nets in 18-49 while leading its rivals in adults (2.5/6).

All three CBS shows dominated their timeslots in total viewers, with “NCIS” beating the combined averages in the 8 o’clock hour of NBC, ABC, Fox, CW and Univision.

Elsewhere, NBC tied Univision for second in 18-49, kicking off the night with episodes of “Betty White’s Off Their Rockers” at 8 (1.4/4 in 18-49, 5.4 million viewers overall) and 8:30 (1.8/5 in 18-49, 5.9 million viewers overall). Though the second seg dipped a tick week to week, 9 p.m. comedy “Go On” (1.7/4 in 18-49, 4.4 million viewers overall) bounced back from its low of last week, rising 13%. And holding steady week to week were “The New Normal” (1.3/3 in 18-49, 3.2 million viewers overall) and “Parenthood” (1.9/5 in 18-49, 5.0 million viewers overall), with the latter leading the major nets in 18-49 for the 10 o’clock hour with the season’s penultimate episode.

For Univision, “Por Ella Soy Eva” (1.8/5 in 18-49, 4.1 million viewers overall) and “Amores Verdaderos” (1.9/5 in 18-49, 4.6 million viewers overall) continue to lead the way.

Fox comedies “Raising Hope” (1.6/5 in 18-49, 3.7 million viewers overall), “Ben & Kate” (1.1/3 in 18-49, 2.3 million viewers overall) and “New Girl” (1.9/5 in 18-49, 3.6 million viewers overall) all edged down week to week, though “New Girl” remained the night’s top comedy in 18-49 and was Tuesday’s No. 1 broadcast program overall in 18-34 (2.1/6).

And at 9:30 p.m., “The Mindy Project” (1.5/4 in 18-49, 2.8 million viewers overall) held steady from last week and led among the half-hour’s three broadcast comedies in 18-49 for second straight week — although last week, the three were all bested in 18-49 by a repeat of “The Big Bang Theory” on TBS.

At ABC, special repeats of “Modern Family” (1.6/5 in 18-49, 5.2 million viewers overall) and “Suburgatory” (1.0/3 in 18-49, 3.2 million viewers overall) led into low-rated comedies “Happy Endings” (1.3/3 in 18-49, 3.1 million viewers overall) and “Don’t Trust the B in Apt. 23” (1.1/3 in 18-49, 2.7 million viewers overall). “Happy” had a weaker lead-in this week, as “Suburgatory” was markedly lower than last week’s special “The Middle” repeat.

And at 10, “Private Practice” (1.2/3 in 18-49, 4.0 million viewers overall) edged up but remained well behind the dramas on NBC and CBS in 18-49; the show ends its six-season run on Jan. 29.

At CW, “Hart of Dixie” returned with its first new episode in five weeks (0.6/2 in 18-49, 1.4 million viewers overall), matching a season high in adults 18-34 (0.7/2). It was followed by “Emily Owens, M.D.” (0.3/1 in 18-49, 1.0 million viewers overall).

Preliminary 18-49 averages for the night: CBS, 2.7/7; NBC and Univision, 1.7/5; Fox, 1.5/4; ABC, 1.2/3; CW, 0.4/1.

In total viewers: CBS, 17.0 million; NBC, 4.8 million; Univision, 4.1 million; ABC, 3.7 million; Fox, 3.1 million; CW, 1.2 million.