NBC’s “Revolution” remains TV’s hottest new show this fall, but the gap between it and its veteran Monday drama rivals — ABC’s “Castle” and CBS’ “Hawaii Five-0” — tightened even more this week.

“Revolution,” of course, is a strong gainer in DVR playback, but its same-night numbers have been declining and the show posted its lowest score to date last night.

According to preliminary national estimates from Nielsen, NBC led among the broadcast networks in key demos Monday behind the night’s top-rated show, “The Voice” (4.3 rating/11 share in adults 18-49, 11.5 million viewers overall), and 10 p.m. drama “Revolution” (2.6/7 in 18-49, 7.1 million viewers overall). In the 18-49 demo, NBC led its rivals in all six of the night’s half-hours, though the gap in the 10 o’clock hour is getting closer as “Revolution” has come back to the pack some — down 7% from last week and 13% from two weeks ago.

ABC’s “Castle” averaged a 2.1/5 in 18-49 and 10.7 million viewers overall), and CBS’ “Hawaii Five-0” (2.0/5 in 18-49, 7.7 million viewers overall) was close behind it, though the former is expected to be revised downward in the nationals due to local-market preemptions in both Pittsburgh and Kansas City for the Steelers-Chiefs game on “Monday Night Football.”

The roughly half a ratings point advantage in 18-49 for “Revolution” would be its smallest of the season. Four weeks ago, its 3.3 rating in the demo was more than 1 point better than both “Castle” and “Hawaii Five-0.”

Elsewhere Monday, CBS saw gains for “How I Met Your Mother” (3.0/8 in 18-49, 7.9 million viewers overall) but declines for lead-out “Partners” (1.8/5 in 18-49, 5.6 million viewers overall), which hit a low. From there, “2 Broke Girls” (3.2/8 in 18-49, 9.0 million viewers overall) and 10 p.m. drama “Hawaii Five-0” were flat week to week, while the 9:30 p.m. comedy between them, “Mike & Molly,” was on the rise (3.0/7 in 18-49, 9.2 million viewers overall). “Mike & Molly” retained a season-best 94% of its “2 Broke Girls” lead-in.

Like “Castle,” numbers for ABC’s “Dancing With the Stars” (2.2/5 in 18-49, 14.3 million viewers overall) are expected to come down in the nationals due to football, though it will stand as the night’s most-watched entertainment series.

Fox dramas “Bones” (1.9/5 in 18-49, 7.0 million viewers overall) and “Mob Doctor” (0.9/2 in 18-49, 3.1 million viewers overall) were both down a tick week to week and the net finished fifth among the broadcasters on the night, edged out by Univision.

At CW, “90210” (0.6/2 in 18-49, 1.2 million viewers overall) and “Gossip Girl” (0.4/1 in 18-49, 0.8 million viewers overall) were both from their low scores of last week.

Preliminary 18-49 averages for the night: NBC, 3.8/9; CBS, 2.5/6; ABC, 2.2/5; Univision, 1.6/4; Fox, 1.4/3; CW, 0.5/1.

In total viewers: ABC, 13.1 million; NBC, 10.1 million; CBS, 7.9 million; Fox, 5.1 million; Univision, 3.7 million.