HOLLYWOOD — NBC has widened its May sweeps demo ratings lead with victories on Thursday, Friday and Saturday — and the net was expecting a nice push Sunday from its 75th anniversary special.

According to Nielsen nationals for Thursday and prelim nationals for Friday and Saturday, the Peacock has bolted out to a 5.2 rating in adults 18-49 through the opening 10 nights of the four-week May sweep. CBS is second (4.3), followed by Fox (3.4) and ABC (3.3) in a close battle for third.

NBC has also assumed the month’s lead in total viewers (roughly 13.3 million), having overtaken CBS (12.8m), which held a slight edge after the opening week.

It was a big night for television’s three hottest shows on Thursday, as NBC’s “Friends” and “ER” and CBS’ “CSI: Crime Scene Investigation” delivered boffo numbers.

NBC won the night with a 10.6 rating in adults 18-49 and 21.2 million viewers overall, with CBS (7.1, 19.1m) the only other net competitive.

The 8 p.m. “Friends” (23.97m, 11.7/32 in 18-49) was up 9% week-to-week in the demo, with the net’s two-hour comedy block jumping by 12% as a whole from last week (9.4 vs. 8.4), when ABC’s “The Bachelor” kept a lid somewhat on the net’s scores.

“Friends” topped “Survivor: Marquesas” by a hearty 67% at 8 and by 16% at 8:30 with a repeat. Reality adventure series was flat week-to-week in 18-49 (7.8/21) and up slightly in viewers (to 19.60m), taking the 8:30 half-hour in viewers and adults 25-54.

“CSI” took control of Thursday’s middle hour for CBS (26.17m, 9.6/23 in A18-49), topping NBC’s comedies by 20% in the demo and by more than 10 million viewers overall. It was the night’s most-watched program.

“ER” (25.79m, 12.9/32) closed out the night big for NBC, more than tripling the demo score of CBS’ disappointing “The Agency” (11.16m, 3.6/9). CIA drama retained just 37% of its “CSI” 18-49 lead-in and a mere 28% of its 12-34 aud.

Fox enjoyed its best Thursday (7.32m, 3.5/9 in 18-49) in four months with the three-hour “Star Wars: Return of the Jedi,” taking some of the male aud away from UPN’s “WWF Smackdown,” which fell to all-time lows (4.48m, 1.8/4). The wrestling skein had never dropped below 5 million viewers.

Fox also saw a slight uptick for its 90-minute season finale of “Dark Angel” on Friday (prelim 5.6m, 2.6/9 in 18-49), but the net still placed third on the night in the demo.

NBC, as usual, won the night but it actually trailed heading into the 10 o’clock hour, before “Law & Order: SVU” (prelim 16.5m, 5.7/18 in 18-49) posted its usual dominating victory.

ABC’s “American Bandstand” took the night’s opening two hours in adults 18-49 (prelim 3.1/11), building throughout its telecast (from 8.1 million to 10.7m and from 2.5/10 to 3.7/12 in 18-49). It also won its timeslot in women 18-49 (3.7/12), adults 25-54 (3.9/12) and men 25-54 (2.9/9).

CBS opened Friday well, with a special “CSI” winning the 8 o’clock hour in 18-49 (3.1/11), but “First Monday” (prelim 1.9/6) and “48 Hours” (prelim 1.6/5) fizzled.

The Eye won Saturday in total viewers despite a fourth-place finish in 18-49. NBC, with an NBA playoff game and a repeat of “Men in Black,” took the night in 18-49 (prelim 3.2/11), ahead of Fox’s regular lineup (2.7/10) and ABC’s quickie repeat of “The Sixth Sense” (2.3/8).