Fox’s “American Idol” continues to lose ratings ground on Wednesday, with ABC’s “Modern Family” appearing to have edged it out as the night’s top show among young adults for the first time. In another first, NBC’s rookie drama “Chicago Fire” edged past CBS vet “CSI” to win the 10 o’clock hour in demos.

According to preliminary national estimates from Nielsen, “American Idol” averaged a 3.8 rating/11 share in adults 18-49 and 13.1 million viewers overall from 8 to 10 p.m., winning three of its half-hours in 18-49 and tying with ABC’s “Modern Family” from 9 to 9:30. And though it again won the night for Fox and was the most-watched program overall, “Idol” did not finish ahead of an original “Modern Family” as Wednesday’s No. 1 show in 18-49 for the first time in the four years they have gone up against each other. (Note that “Idol” is expected to round up in the nationals to a 3.9, but even a tie would be a first for “Modern Family,” which has beaten “Idol” in Live+7 numbers in the past.)

The 3.8 or 3.9 demo rating reps another Wednesday performance low for “Idol,” which had earned a 4.1 last week, a 4.3 two weeks ago and a 4.6 three weeks ago.

Elsewhere, CBS ran second as “Survivor” (2.6/7 in 18-49, 9.4 million viewers overall) was up week to week to close the gap some with “American Idol.” It was followed by “Criminal Minds” (2.6/7 in 18-49, 10.6 million viewers overall), which held steady and ranked second or third for the 9 o’clock hour in various categories, and “CSI” (1.8/5 in 18-49, 9.3 million viewers overall) which hit a low and was down 22% from last week. “CSI” still led its hour in 25-54 (2.7/7) and total viewers.

At ABC, “The Middle” (2.1/6 in 18-49, 8.0 million viewers overall) and “The Neighbors” (1.7/5 in 18-49, 6.1 million viewers overall) were both down week to week, placing third in the 8 o’clock hour. From there, “Modern Family” surged as usual and was in line with its performance of the last two weeks, ruling as the night’s No. 1 show in 18-49 and 25-54 (tied with “Idol”). “Suburgatory” was up at 9:30 p.m. (2.3/6 in 18-49, 6.3 million viewers overall) and placed third in 18-49, but “Nashville” hit a low (1.6/4 in 18-49, 5.1 million viewers overall) one week after being preempted for an Oscar special.

NBC edged up week to week from 8 to 9 p.m. with “Whitney” (1.2/4 in 18-49, 3.5 million viewers overall) and the season finale of “Guys With Kids” (1.1/3 in 18-49, 3.1 million viewers overall) and was flat week to week from 9 to 11 p.m. with dramas “Law & Order: SVU” (1.6/4 in 18-49, 5.6 million viewers overall) and “Chicago Fire” (1.9/5 in 18-49, 6.5 million viewers overall). “Fire” edged out an original episode of “CSI” for the first time in 18-49 after tying it once earlier this season.

CW dramas “Arrow” (1.0/3 in 18-49, 3.3 million viewers overall) and “Supernatural” (0.9/2 in 18-49, 2.2 million viewers overall) were up a bit week to week, with the former tying NBC’s comedies in the hour among adults 18-34 (0.8/3).

Preliminary 18-49 averages for the night: Fox, 3.8/11; CBS, 2.4/6; ABC, 2.2/6; Univision, 1.7/5; NBC, 1.6/4; CW, 0.9/3.

In total viewers: Fox, 13.1 million; CBS, 9.8 million; ABC, 6.9 million; NBC, 5.2 million; Univision, 3.9 million; CW, 2.7 million.