The final Tuesday of the television season was an active one, with Fox prevailing behind “American Idol” and ABC rolling in the final two hours with the conclusion of “Dancing With the Stars.” CBS was also competitive, with “The Mentalist” wrapping its rookie season with a good performance.

It’s difficult, meanwhile, to draw much of a conclusion regarding the tune-in for Fox’s preview of musical comedy “Glee,” which had a decent showing following “American Idol” but, not surprisingly, declined in its second half-hour. Tuesday’s telecast was more about generating buzz for the unconventional show, which won’t air again until the fall, when it airs behind “So You Think You Can Dance.”

Fox marketing chief Joe Earley said he considered the launch a success from a promotional perspective. Given the show’s competish, he said the net wasn’t bothered by the numbers.

“We did the projections, we knew what was in the time period,” he said. “No one thought this would take down either big show for their finale.”

Looking at the numbers, Fox cruised early with “American Idol,” which averaged an 8.6 rating/25 share in adults 18-49 and 23.82 million viewers overall from 8 to 9:03 p.m., beating its combined network competition in 18-49 during the 8 o’clock hour. Despite its dominance, this was the lowest-rated final “Idol” performance show to date in 18-49, coming in 15% below last year’s score (10.1/28).

Following “Idol” the preview of “Glee” (3.9/10 in 18-49, 9.62m from 9:03 to 10:02 p.m.) placed third in the 9:30 half-hour among adults 18-49 (3.6/9) after averaging a 4.4/12 from 9:03 to 9:30. 

Show fared best relative to “Idol” among its target younger audience, retaining 52% in those 12-34 (3.2/10 vs. 6.2/21) to win the hour in this demo.

Earley said he could already see the viral impact of “Glee” online; the Journey song “Don’t Stop Believing,” which is performed at the end of the “Glee” pilot, quickly shot to the top of the iTunes download chart.

“The point of this was to get people to see it, because we would not have had the opportunity again (to reach as many viewers),” he said. “The best way to market this show was to have people watch it.”

At ABC, following a “Dancing With the Stars” recap special at 8 p.m. (1.8/5 in 18-49, 7.65m), the two-hour “Dancing” season finale averaged a slot-leading 5.2/14 in 18-49 and 20.31 million viewers overall, making it the No. 2 show of the night behind “Idol.”

Despite ratings declines this season, “Dancing” hit a Wednesday season high and was up a tick in the demo vs. its fall finale in November, while coming in just below last May’s spring season-ender (5.4/14).

CBS ran second to “Idol” in Tuesday’s leadoff hour with the season finale of “NCIS” (3.4/10 in 18-49, 16.51m) and then built some at 9 p.m. with the season-ender of “The Mentalist” (3.7/10, 16.82m), which placed third for its hour in 18-49 and second in both adults 25-54 and total viewers. Closing things out was the series finale of “Without a Trace” (2.5/7, 11.21m).

NBC was barely a blip on the ratings radar with the special “Most Outrageous Moments” (0.9/3 in 18-49, 3.00m) and a repeat “Law and Order: SVU” (1.2/3 in 18-49, 3.49m). Even the season finale of “SVU” at 10 was weak (2.5/7, 6.93m), placing third or fourth in most categories.

CW was down a bit week to week with the finales of “Reaper” (0.7/2 in 18-49, 1.71m) and “90210” (1.1/3, 2.00m), though the latter continues to score well in the net’s core aud of women 18-34 (2.4/7).

On cable, ESPN’s opening game of the NBA’s Western Conference finals between the Los Angeles Lakers and Denver Nuggets averaged a big 3.6/10 in 18-49 and 8.09 million viewers overall. It placed second in 18-49 to “Dancing” during the 10 p.m. hour.

(Michael Schneider contributed to this report.)