NBC’s Broadway-themed drama “Smash” opened to good ratings Monday, airing behind the timeslot debut of “The Voice,” which followed up its monster post-Super Bowl premiere one night earlier with very impressive numbers. The shows combined for easily the net’s top non-sports night of the season as it swept all six half-hours among young adults.

It will take a while to see where both shows settle, but NBC has to be pleased with the launch of “Smash,” which averaged a 3.8 rating/10 share in adults 18-49 and 11.5 million viewers overall, according to affiliate-based preliminary estimates from Nielsen. Though it fell off in its second half-hour as expected (from 4.2 to 3.4 in 18-49), “Smash” led its hour over competing dramas “Hawaii Five-0” on CBS (2.7/7 in 18-49, 9.8 million viewers overall) and “Castle” on ABC (2.0/5 in 18-49, 8.7 million viewers overall) — both of which matched season lows in 18-49.

No regular 10 p.m. drama on any network this season has posted a higher 18-49 score than “Smash’s” premiere, and the only new drama to open bigger in 18-49 was ABC’s “Once Upon a Time” (4.0/10) in October.

“Smash” generated perhaps the best reviews of any drama this season. The show, whose exec producers include Steven Spielberg, Craig Zadan and Neil Meron, stars Debra Messing, Anjelica Huston and Katharine McPhee

Meanwhile, “The Voice” (6.6/16 in 18-49, 17.9 million viewers overall) ruled its two-hour timeslot, easily surpassing its first-season highs last spring in both 18-49 (5.7/15) and total viewers (14.4 million). The NBC music competition opened within shouting distance of Fox’s “American Idol,” which kicked off its season last month with a 7.4/19 in 18-49 and 21.93 million viewers overall – low by its standards. NBC hasn’t done better from 8 to 10 p.m. on Monday with regular series since 2004.

NBC won Monday, a night on which it has really struggled this season, in all key categories including adults 18-49 (5.7/14). One year earlier, with a lineup of “Chuck,” “Cape” and “Harry’s Law,” the net averaged a mere 1.6/4 in the demo.

Elsewhere, CBS and ABC held up well, with the Eye getting more good comedy scores from “How I Met Your Mother” (4.0/11 in 18-49, 10.0 million viewers overall), “2 Broke Girls” (4.3/11 in 18-49, 11.4 million viewers overall) and “Two and a Half Men” (4.2/10 in 18-49, 16.8 million viewers overall). Also solid but not quite as strong as the others was 9:30 p.m. soph “Mike & Molly” (3.4/8 in 18-49, 11.0 million viewers overall).

And at ABC, “The Bachelor” (2.6/6 in 18-49, 8.2 million viewers overall) was flat week to week despite the stronger NBC competition.

Fox’s drama combo of “House” (2.4/6 in 18-49, 7.2 million viewers overall) and “Alcatraz” (2.2/5 in 18-49, 6.8 million viewers overall) suffered the most, placing fourth from 8 to 10. “Alcatraz” lost about 20% of its week-earlier audience.

CW’s “Gossip Girl” (0.6/2 in 18-49, 1.3 million viewers overall) and “Hart of Dixie” (0.6/1 in 18-49, 1.5 million viewers overall) were in line with last week.

Preliminary 18-49 averages for the night: NBC, 5.7/14; CBS, 3.5/9; ABC, 2.4/6; Fox, 2.3/6; Univision, 1.6/4; CW, 0.6/1.

In total viewers: NBC, 15.6 million; CBS, 10.8 million; ABC, 8.4 million; Fox, 7.0 million; Univision, 3.8 million; CW, 1.4 million.