The “Friends” frenzy began one night early for NBC, which scored big Wednesday with a two-hour “Dateline” spec on the departing laffer.

Peacock net came up just short of “American Idol”-fueled Fox for the night in adults 18-49 but closed out the first week of the May sweep with leads in all key ratings categories.

One-week averages in adults 18-49 had NBC well out in front with a 5.3 rating/15 share (up 20% in rating vs. last year), followed by Fox (4.0/11, down 9%), CBS (3.5/10, even), ABC (2.8/8, down 13%), the WB (1.6/5, down 11%) and UPN (1.1/3, down 21%).

NBC also leads in adults 25-54 (6.0/15), adults 18-34 (4.6/15) and total viewers (13.1 million).

On Wednesday from 9 to 11, “Dateline,” featuring Katie Couric and Matt Lauer interviews of the six “Friends” stars, delivered a first-place 6.5 rating/17 share in adults 18-49 and 14.71 million viewers overall — the net’s best numbers in the time period since September.

Leading into “Dateline” were a pair of repeat “Friends” from April that scored a second-place 3.7/12 in 18-49.

Fox led in 18-49 at 8 with “That ’70s Show” (4.5/15) and dominated across the board at 8:30 with “American Idol” (8.8/25 in 18-49, 21.18m). “The OC” (4.7/12 in 18-49, 10.72m) closed out its season by tying ABC’s “The Bachelor” for second in 18-49 and dominating the 9 o’clock hour in persons 12-34 (6.1/18).

ABC was paced by its unscripted combo of “The Bachelor” (4.7/12 in 18-49, 10.33m) and “Extreme Makeover” (4.3/11 in 18-49, 10.08m), CBS by a special 10 p.m. repeat of “CSI” (4.4/11 in 18-49, 13.33m).

Also of note was a nice surge for the WB’s “Angel” (2.6/7 in 18-49, 4.68m), which is nearing its May 19 series finale. It matched or set several season highs, building on its 12-34 “Smallville” lead-in (2.8/8 vs. 2.5/9).

For the night, Fox’s 5.7/16 in adults 18-49 edged out NBC’s 5.6/15. The Peacock led in adults 25-54 (6.2/15), Fox in total viewers (12.9 million).