CBS comfortably took Monday’s primetime ratings race as its comedy block — led by “Two and a Half Men” and “The Big Bang Theory” — had one of its strongest showings of the season. Meanwhile, NBC’s 9-11 p.m. dramas “Trauma” and “Law & Order” looked weak in their first try as skedmates.

According to preliminary nationals from Nielsen, CBS claimed the night’s top two shows in “Two and a Half Men” (5.8 rating/15 share in adults 18-49, 17.5 million viewers overall) and “The Big Bang Theory” (5.8/15 in 18-49, 16.3 million viewers overall), with the former hitting a season high in the demo. The night’s opening-hour of comedies, “How I Met Your Mother” (3.9/11 in 18-49, 10.3 million viewers overall) and “Rules of Engagement” (3.6/9 in 18-49, 10.1 million viewers overall), was also above average, but 10 p.m. drama “CSI: Miami” was on the low side (3.3/10 in 18-49, 11.9 million viewers overall) but still led its hour rather easily.

Fox finished second, as “House” (4.8/13 in 18-49, 12.8 million viewers overall) returned to action a winner although it was a bit below average, and “24” took advantage of its stronger lead-in to perform better than in recent weeks (2.8/7 in 18-49, 8.9 million viewers overall).

ABC’s special “The Bachelor: Jason and Molly’s Wedding” (2.7/7 in 18-49, 9.3 million viewers overall) didn’t come close to the kind of numbers the hot franchise has been putting up lately but helped keep the net in the game from 8 to 10. And “Castle” (2.4/7 in 18-49, 9.1 million viewers overall) continues to perform pretty well at 10 despite now facing two other crime shows.

NBC was a distant fourth, getting its best numbers from “Chuck” (2.3/6 in 18-49, 6.3 million viewers overall), which was up year to year, before fading with “Trauma” (1.4/3 in 18-49, 4.8 million viewers overall) and “Law & Order” (5.2 million viewers overall). Rookie “Trauma” struggled with its first original episode since Nov. 30, and “Law & Order” declined following its stronger new-night premiere a week ago and finished in line with the net’s Monday average with “The Jay Leno Show.”

At CW, “Life Unexpected” (0.9/2 in 18-49, 2.0 million viewers overall) held up well in its first try leading off the night, rising a bit vs. the previous week when it aired at 9 o’clock; the drama competition for young femmes is also tougher in its new hour opposite “House” on Fox and “The Secret Life of the American Teenager” on ABC Family. And “Gossip Girl” (1.0/2 in 18-49, 1.8 million viewers overall) returned after a three-month break with nothing-special numbers, although it did beat NBC’s “Trauma” in adults 18-34.

Preliminary 18-49 averages for the night: CBS, 4.3/12; Fox, 3.8/10; ABC, 2.6/7; NBC, 1.7/5; Univision, 1.4/4; CW, 0.9/2.

In total viewers: CBS, 13.0 million; Fox, 10.8 million; ABC, 9.2 million; NBC, 5.4 million; Univision, 3.7 million; CW, 1.9 million.