With a return to dominance by its battle-weary Thursday lineup, NBC has put an exclamation point on its seventh straight May sweeps victory among young adults.

Beckoned by promos that promised big plotline twists on their favorite shows, viewers turned out in huge numbers for the season finales of “Friends” and “ER” on Thursday, while the season ender for “Will & Grace” also ruled its time period but was not nearly as commanding. NBC won the night over second-place CBS by a whopping 26 shares in adults 18-49 and by 14.3 million viewers overall, according to Nielsen.

“Friends” won its hour by 36 shares in adults 18-49, “ER” by 31 shares and “Will & Grace” by 14 shares.

The big night has given the Peacock web an unassailable 22% advantage for the month over second-place Fox and CBS in adults 18-49 (projected 4.9 to 4.0) with just four nights left to be counted. The victory would be NBC’s fourth straight in a major sweep and its seventh straight in May (including a tie with ABC last year).

In total viewers, NBC has also closed the gap with CBS, but the Eye still leads by roughly half a million viewers (12.6 million to 12.1m) and is poised for its first May sweeps victory by this measure in at least 15 years.

It’s going to be a closer down-to-the wire finish, meanwhile, in the seasonlong battle for most viewers overall. Factoring in prelim nationals for Friday and Saturday, CBS took a roughly 12,000-viewer advantage over ABC into Sunday night’s action (12.519m vs. 12.507m).

NBC’s one-hour finales on Thursday gave the network its highest rating in adults 18-49 (14.3/36) on any night this season. Net was off by 15% vs. last year (16.8/43), though, with most of the losses attributable to a 31% decline by “Will & Grace” (11.8/29) vs. last May’s Niles and Daphne-fueled “Frasier” finale (17.0/41).

“Friends” (30.05m, 15.7/43 in A18-49), which had been battered a bit this season by CBS’ “Survivor: The Australian Outback,” was off just 2% in the demo vs. a year ago. Comedy delivered a whopping 57 share in women 18-34 in its final half-hour.

‘ER’ demo dip

“ER” dominated its hour but was off by 13% year-to-year in adults 18-49 (15.3/38 vs. 17.5/44). This is also the first time in at least the last two seasons — and likely ever — that a firstrun episode of the medical drama has logged a lower demo rating than a firstrun “Friends” on the same night.

Though CBS made significant Thursday gains this season thanks to “Survivor” and “CSI: Crime Scene Investigation,” NBC points out that its own first-place standing on the night was minimally affected. Net’s 9.7 rating in adults 18-49 on the night this season is off a scant 2% from last year’s 9.9, when ABC (with “Who Wants to Be a Millionaire”) was the net hounding the Peacock.

CBS received a strong perf Thursday from the season finale of “CSI” (18.98m, 6.4/15 in A18-49), which finished second to “Will & Grace” across the board at 9, but a repeat “CSI” and an original “48 Hours” at 10 couldn’t do much opposite NBC’s biggies. Still, on the strength of the original “CSI” alone, CBS was up year-to-year for the night by 70% in adults 18-49 (3.9 vs. 2.3).

None of the other nets could do much, with ABC claiming third place in adults 18-49 (2.6/7), followed by UPN (2.5/6), Fox (2.4/6) and the WB (1.9/5).

NBC scored narrow victories on Friday (prelim 11 million viewers, 3.5/12 in adults 18-49) despite the weakest primetime turnout ever for the “Daytime Emmy Awards” (prelim 10.3m, 3.5/11 in A18-49). Compared with last season’s show on ABC, the kudocast was down by nearly 20%.

Providential Friday

The season finale of “Providence” helped keep the night in NBC’s column, as it logged its best marks (prelim 12.4m, 3.8/14 in A18-49) since March 30 and took its hour by 4 shares in the demo over second-place ABC and Fox (prelim 2.7/10 each).

ABC had its best Friday of the sweep, finishing second in adults 18-49 and first in total viewers from 9-11 opposite the Emmys. “Who Wants to Be a Millionaire” was the night’s most-watched program (prelim 13.4m).

The television premiere of “There’s Something About Mary” gave Fox the night in adults 18-34 (3.5/14) but settled for a second-place finish in adults 18-49 (3.2/11) and third in total viewers (7.4 million). That was still much better than the puny fourth-place finishes for the network preem of “Batman & Robin” on CBS (prelim 5.7m, 2.4/8 in A18-49).

Don’t mess with ‘Walker’

The Eye fared better on Saturday with the two-hour series finale of “Walker, Texas Ranger,” which gave the net its best series scores on the night from 8-10 p.m. (prelim 10.6m, 2.7/10 in A18-49) since March 2000. CBS won the night in total viewers (prelim 11.3m) and adults 25-54 (prelim 4.0/12).

NBC will likely sneak past CBS and Fox to take Saturday in adults 18-49 when nationals are issued. Peacock’s coverage of Game 1 of the NBA’s Western Conference finals averaged a 7.0/15 households rating in overnights — a 13% gain vs. last year’s 6.2/15 for Game 1 of the Lakers-Portland series.

Fox, with “Cops” and “America’s Most Wanted,” will likely finish second by most measures for the night (including a 2.9/10 in A18-49), while ABC will run fourth with a repeat of “The Bodyguard” (prelim 6 million, 2.2/7 in A18-49).