Fast National ratings for Monday, January 18, 2010.

In its Monday premiere, FOX's "24" delivered OK numbers, while The CW got a strong launch for the series debut of "Life Unexpected." Neither of those things made a difference as CBS dominated the second half of the evening for Monday wins in most key measures.

Among adults 18-49, CBS averaged a 4.2 rating, beating the 3.5 rating for ABC and FOX's 3.4 rating in the key demographic. NBC was a distant fourth with a 1.9 rating, leaving The CW's 1.1 rating in fifth.

Overall, CBS averaged an estimated 12.94 million viewers to go with a 7.7 rating/12 share. ABC's 6.5/10 nipped the 6.4/9 for FOX, though FOX averaged more total viewers. NBC was well back in fourth with a 3.1/5. The CW's 1.6/2 was good for fifth.

ABC started the night in first with a 6.4/10 for "The Bachelor." CBS' "How I Met Your Mother" and "Accidentally on Purpose" were second overal with a 6.0/9 and first in the key demo with a 3.7 rating. The first hour of FOX's "24" was third with a 6.1/9. NBC's "Chuck" was fourth with a 3.9/6 and a 2.5 rating in the demo. The CW's "One Tree Hill" return finished fifth.

CBS moved into first at 9 p.m. with the 9.1/13 for "Two and a Half Men" and "The Big Bang Theory," which also combined to win the hour in the key demographic with a 5.3 rating. [Odd note on the CBS numbers: For the first time in weeks, "Two and a Half Men" beat "Big Bang Theory" among adults 18-49.] ABC's "The Bachelor" was second overall and in the demo. FOX's "24" improved to a 6.6/10 in its second hour. On NBC, "Heroes" had a 2.4/4 and a 1.8 rating in the demo. The CW's premiere of the critically adored "Life Unexpected" did a 1.7/3, averaging 2.74 million viewers and a 1.2 demo rating, all pretty good by the netlet's standards.

"CSI: Miami" had an 8.2/14 and a 3.6 demo rating to close the night in first for CBS. ABC's "Castle" did a 6.0/10 for second. NBC's "The Jay Leno Show" trailed.

All ratings information comes from preliminary Fast National Nielsen data, which includes live and same-day DVR viewing. All numbers are subject to change.