The “American Idol” locomotive powered Fox to another primetime weekly victory in key demos, but the good news for the other nets is that their new skeins are enjoying a nice start to spring.

CBS is looking good after two airings with drama “The Unit” and comedy “The New Adventures of Old Christine,” NBC gamer “Deal or No Deal” continues to build, and ABC got off to a sturdy start last week with unscripted competish “American Inventor.”

“Christine” and “Deal” were both on the rise on Monday of the current week.

Fox, meanwhile, isn’t faring as well with new comedies “Free Ride” and “The Loop,” but the net is keeping its foot on the accelerator in the season’s second half with “Idol” and “24.”

Overall, according to Nielsen in-home viewing estimates, Fox prevailed for the week ended Sunday with a 4.9 rating/13 share in adults 18-49, followed by CBS (3.9/11), ABC (3.4/9) and NBC (3.1/8). Murdoch net also ruled in adults 25-54 (5.3/13) and people 12-34 (4.2/13) while placing second in total viewers (11.6 million) to CBS (12.2 million).

Fox, which has won four straight weeks in 18-49, was up a nifty 20% vs. the same week a year ago.

A two-hour “American Idol” episode Tuesday was easily the week’s No. 1 program (13.7/33 in 18-49, 32.77 million viewers overall) — and the top-scoring performance edition in the show’s history — while Wednesday’s results show ranked second (11.5/28, 28.09m).

Also, Monday’s “24” (5.8/14 in 18-49, 13.72m) continues to outpace last year’s averages and Wednesday’s “Bones” looked good in its first regular 8 o’clock airing (4.4/12, 12.07m).

On the comedy front, “The Loop” drooped in its regular slot Thursday (2.0/6, 4.75m) after more than three times as many viewers sampled it the previous night after “Idol.” And Sunday’s “Free Ride” remains on the low side (3.0/7, 5.29m), although it edged up a tick week to week.

At CBS, “Old Christine” (4.8/11, 15.09m) had a perky preem perf on Monday (Daily Variety, March 15), and “The Unit” (4.9/11, 18.07m) held up very well in its second outing, airing behind one of the best scores to date for “NCIS” (4.4/11, 17.55m).

Most of the Eye’s weekend was devoted to the NCAA men’s basketball tournament. Thursday’s early primetime window had its best showing in four years (3.3/10 in 18-49, 9.37m), and all other windows on Friday and Saturday were up year to year.

ABC surged 17% above the same week a year ago, getting a nice lift from Thursday’s two-hour series premiere of “American Inventor” (5.4/15, 14.15m), which contributed to the net’s first in-season Thursday victory in 18-49 (with series) in at least 15 years.

The Alphabet also ruled Sunday with “Grey’s Anatomy” (9.3/23 in 18-49, 21.13m) and “Extreme Makeover: Home Edition” (6.4/16, 16.21m). And in between, a repeat of “Desperate Housewives” (5.2/12, 13.55m) led its hour over HBO’s “The Sopranos” (4.4/10, 9.18m).

ABC continues to struggle Fridays with “In Justice” (1.6/5 in 18-49, 6.51m) and saw Tuesday laffer “Sons & Daughters” (1.9/4 in 18-49, 5.15m for the hour) take a dive opposite “American Idol.”

Fourth-place NBC was paced by Thursday’s “ER” (5.8/15, 13.98m) and Monday’s “Deal or No Deal” (5.3/14, 15.52m). But it didn’t do a whole lot with its Saturday wrestling special “WWE Saturday Main Event” (1.8/6, 5.22m from 8 to 10), faring slightly better than the previous night’s “WWE Smackdown” on UPN (1.5/5, 4.27m).

Opposite hoops instead of dramas on CBS, NBC’s Friday combo of “Las Vegas” (3.3/10, 10.12m) and “Conviction” (3.0/9, 9.11m) were both on the rise.

And with “America’s Next Top Model” (2.3/6, 4.87m) back in the fold, UPN had no trouble topping a repeat-riddled the WB in their target 18-34 demo (1.4/4 to 1.0/3).

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On Monday of the current week, comedy “Old Christine” (5.1/12 in 18-49, 15.13m) matched or established season highs in key categories for CBS at 9:30, rising 6% in 18-49 from its premiere and retaining a strong 94% of its lead-in from “Two and a Half Men” (5.4/13, 16.72m).

Combined with “CSI: Miami” (6.6/17, 19.86m), the night’s top show, CBS won in both 18-49 and 25-54.

Over at NBC, “Deal or No Deal” attained a new high for a third straight week (5.6/14, 16.80m from 8 to 9:02), helping “The Apprentice 5” edge up to a high (fourth-place 4.1/9, 10.21m).

Fox welcomed the return of “Prison Break” (4.3/11, 10.27m), which nabbed the 8 o’clock hour’s strongest regular-slot score of the season. That led into “24” (5.5/13, 13.71m), which topped its hour in 18-49 and key male demos.

ABC was paced by the highest-rated “Supernanny” of the season at 9 (third-place 4.4/10, 10.92m).