Fox’s ”American Idol” easily led its two hours in young adults with Tuesday’s special episode. Most competing shows lost demo ground but the CBS ”NCIS” shows performed well, and the night’s final hour saw NBC’s ”Parenthood” wrap its season with an upswing.

According to preliminary national estimates from Nielsen, ”American Idol” averaged a 5.0 rating/13 share in adults 18-49 and 15.8 million viewers overall, on par with its two-hour Wednesday of last week. Tuesday’s special episode, in which the 12 male finalists performed, did about 80% better than the net’s regular lineup of last week. From 8 to 10 p.m., ”American Idol” beat runner-up CBS by 56% in adults 18-49 (5.0 to 3.2) and by 37% in adults 25-54 (6.3 to 4.6).

At CBS, ”NCIS” (3.4/9 in 18-49, 18.0 million viewers overall) was dinged a bit by ”Idol” but pulled to within 3 shares of it in adults 25-54 while beating the music competition in total viewers , something it never did when the shows faced each other on Tuesday for several years. ”NCIS: Los Angeles” followed with a strong performance (3.1/8 in 18-49, 15.7 million viewers overall), bouncing back by 15% from last week’s season low to place second across the board in the 9 o’clock hour; the two ”NCIS” shows combined to beat ”Idol” head-to-head in total viewers for the two-hour block. And at 10, ”Unforgettable” (1.9/5 in 18-49, 9.9 million viewers overall) was down a tad week to week, tying for the hour’s 18-49 lead.

Opposite tough reality competition, NBC’s ”The Biggest Loser” dropped to season lows (2.0/5 in 18-49, 5.7 million viewers overall), but ”Parenthood” (1.9/5 in 18-49, 5.1 million viewers overall) had its best demo score since Nov. 29 with its 18th and final episode of the season. The family drama, a strong performer among upscale viewers and a sizable gainer in DVR playback, figures to return for a fourth season in the fall.

Fourth-place ABC saw ”Last Man Standing” (2.1/6 in 18-49, 7.4 million viewers overall), ”Cougar Town” (1.5/4 in 18-49, 4.3 million viewers overall) and ”The River” (1.5/4 in 18-49, 4.1 million viewers overall) all edge down to season lows, and ”Body of Proof” closed out the night with a below-average delivery (1.3/4 in 18-49

CW aired a special repeat of ”Hart of Dixie” (0.3/1 in 18-49, 0.9 million viewers overall) and original ”Ringer” (0.4/1 in 18-49, 1.1 million viewers overall).

Preliminary 18-49 averages for the night: Fox, 5.0/13; CBS, 2.8/7; NBC, 2.0/5; ABC, 1.6/4; NBC, 1.5/4; CW, 0.4/1.

In total viewers: Fox, 15.8 million; CBS, 14.5 million; ABC, 5.6 million; NBC, 5.5 million; Univision, 3.7 million; CW, 1.0 million.