The Academy Awards may have drawn the week’s largest overall audience, but “American Idol” topped the kudocast in demos and helped Fox cruise to another ratings victory.

ABC’s coverage of the Oscars hit ratings lows on Sunday (Daily Variety, Feb. 26), according to Nielsen, although it’s still easily the net’s top-rated program of the season (10.7 rating/26 share in adults 18-49, 32.01 million viewers overall).

With “American Idol” accounting for one-third of its schedule, though, a Fox victory was never in doubt, and the Murdoch net prevailed for a seventh consecutive frame in adults 18-49. For the season, Fox, with a 4.3 rating, towers over ABC, CBS and NBC, which are all tied at a 3.1.

Looking at the Feb. 18-24 sesh, Fox averaged a big 5.7 rating/15 share in the 18-49 demo, followed by ABC (3.2/8), NBC (2.3/6), CBS (2.1/6), Univision (1.7/4), USA (1.0/2) and CW (0.9/2).

Fox also won handily in adults 25-54 (6.4/15), persons 12-34 (4.3/13) and total viewers (14.96 million) — and it holds the season advantage in these categories as well.

As the 24 “American Idol” finalists took to the stage, two-hour editions on Tuesday (11.3/27 in 18-49, 29.01m) and Wednesday (11.2/27, 28.88m) drew nearly identical scores to claim the week’s top two spots in the 18-49 program rankings.

The first “Idol” results show also padded Fox’s numbers on Thursday (8.5/22 in 18-49, 23.37m), ranking fourth for the week in 18-49 and helping the show behind it, “Don’t Forget the Lyrics,” achieve series highs (4.8/11, 12.43m).

Also, Fox effectively counterprogrammed the Oscars on Sunday with a second-place finish courtesy of NASCAR’s Sprint Cup race (4.1/11 in 18-49, 10.92m).

For ABC, the Academy Awards telecast came in 24% below last year in 18-49 (14.1/33) and 20% lower in total viewers (40.18m). Show saw similar declines in various demo groups, with teens slipping the least (15%).

“Oscar’s Red Carpet,” airing at 8 o’clock in most of the country, ranked fifth for the week (6.3/17 in 18-49, 21.54m), while the “Barbara Walters Special” cracked the top 20 (3.2/9, 11.69m).

Net didn’t have much else to shout about aside from Thursday’s “Lost” (5.7/13 in 18-49, 13.65m), although it had some rare good news on Friday. Despite starting the night in sixth place in demos with a “Grey’s Anatomy” repeat (1.0/3 in 18-49, 3.64m), the second hour of “20/20” at 10 o’clock (featuring the popular “What Would You Do” ethical dilemmas) rallied to a slot-leading 2.9/8 in 18-49 and 8.66 million viewers — the show’s best numbers in more than a year.

NBC started the week strong with “Deal or No Deal” (5.2/13 in 18-49, 16.95m) but didn’t have a whole lot else going for it. Friday’s debut of gameshow “Amnesia” did reasonably well (2.4/7, 7.44m), though.

CBS was led by “Survivor” (4.1/10 in 18-49, 12.66m), which took a shot opposite “American Idol,” and also received good numbers Friday for Drew Carey’s first primetime hosting gig on “The Price Is Right” (2.5/8, 9.35m). On the down side, Tuesday drama “Jericho” (2.0/5, 5.86m) took a tumble in its second week back.

At the CW, “America’s Next Top Model” returned to lower-than-usual numbers (1.9/5, 3.81m), but it lifted the net to its strongest week of 2008. Also of note, Thursday’s “Supernatural” (1.3/3, 3.23m) matched its season high in 18-34 (1.4/4).

Univision ranked third for the week in 18-34 (1.9/6), led by Thursday’s “Premio Lo Nuestro” (2.8/7, 6.24m).

USA led the cablers in primetime thanks in part to “Monk,” which closed its sixth season Friday with its largest aud to date on the net (6.88 million). Show, which was recently picked up for a seventh season, will also be airing repeats on NBC this spring.

ESPN moved up to second in 18-49 on the strength of Saturday’s college basketball matchup between No. 1 Memphis and No. 2 Tennessee (1.9/6 in 18-49, 5.28m). It drew the largest aud on record for a college hoops game on the cabler.

Nickelodeon kicked off the week in a big way with Monday movie “Fairly Odd Baby,” which drew a big 8.81 million viewers to outdraw programming on ABC and CBS.

CNN ranked sixth among cablers for the week in adults 25-54 and fifth in total viewers. Thursday’s Democratic debate from Texas drew 7.68 million viewers, ranking second on cable this election season behind only the Jan. 31 California Democratic debate on CNN (8.32m).

The news nets all got a serious boost this month from increasingly intense political coverage, with Fox News (No. 3 despite airing no debates) and CNN (No. 4) both in the top 10 among total viewers and MSNBC 62% higher than last year at No. 27.

(Sam Thielman contributed to this report.)