CBS won Tuesday’s primetime ratings race in key demos — and beat the combined broadcast competition in total viewers — behind some of the season’s best scores for “NCIS,” while NBC’s “Parks and Recreation” returned for its final season up from its year-ago premiere and was the night’s top comedy. And at ABC, “Marvel’s Agent Carter” fell off by about 20% in its second week but placed second in its timeslot.

According to preliminary national estimates from Nielsen, “NCIS” averaged a 2.8 rating/9 share in adults 18-49 and 19.6 million viewers overall in the 8 o’clock hour, matching last week’s demo delivery as the show’s top performance since its season premiere in September. It was Tuesday’s top show in 18-49, 25-54 (4.2/11) and total viewers.

CBS lost some steam as the night went on, but both “NCIS: New Orleans” (2.2/6 in 18-49, 16.1 million viewers overall) and “Person of Interest” (1.6/5 in 18-49, 10.0 million viewers overall) led their timeslots. “NCIS: New Orleans,” which was picked up by CBS for a second season earlier this week, fell 0.3 from last week, and its 79% retention of “NCIS” in 18-49 matched its season low.

For the night in total viewers, CBS drew more than ABC, NBC, Fox and CW combined. This was the second largest overall audience of the season for “NCIS,” behind only the previous week.

Elsewhere, NBC’s “Parks and Recreation” averaged a 1.5/5 in 18-49 and 3.8 million viewers overall for its season premiere at 8 and then did similar numbers for a second original at 8:30 (1.5/4 in 18-49, 3.3 million viewers overall). This is up 15% (0.2) from its most recent season premiere in September 2013 and matches the show’s best score since its fifth-season finale in May 2013 (behind “The Office”). While still not great numbers (and it placed fourth in its timeslot), it was the top-rated among Tuesday’s five comedies in 18-49 and outperformed every NBC comedy episode since the second week of “Marry Me” (behind “The Voice”) in October.

“Marry Me” has fallen off sharply, though, and despite a solid comedy lead-in on Tuesday, it fell to its series low — down a tick from last week and delivering just half the young-adult audience of comedy timeslot competitor “New Girl” on Fox (1.4/4 in 18-49, 2.9 million viewers overall), which was down a tenth from last week. “About a Boy” picked up a bit from its lead-in at 9:30 p.m. (0.9/2 in 18-49, 2.8 million viewers overall), and was up a tenth from last week, but still lagged in the demo Fox’s “The Mindy Project” (1.1/3 in 18-49, 2.4 million viewers overall), which was up a tick.

NBC picked things up at 10 p.m. with “Chicago Fire” (1.5/5 in 18-49, 6.6 million viewers overall), which finished a tick behind “Person of Interest” in 18-49 despite a significantly smaller lead-in but did hit a season low. Both “Fire” and “Person” remained well in front of ABC’s “Forever” (1.0/3 in 18-49, 4.6 million viewers overall), which continues to do just well enough to stay on the schedule.

Over at ABC, a special “Shark Tank” original at 8 did solid numbers (1.8/6 in 18-49, 7.3 million viewers overall), edging ahead of Fox’s recently renewed “MasterChef Junior” (1.7/5 in 18-49, 4.9 million viewers overall) for second place in the hour among adults 18-49 and 25-54. Despite the additional reality show competition this week from “Shark Tank,” “MasterChef Junior” was within a tick of its week-ago season premiere/

“Shark Tank” was followed on ABC by the second week of limited-run series “Marvel’s Agent Carter” (1.5/4 in 18-49, 5.1 million viewers overall), which was down 21% (0.4) from its week-earlier two-hour series premiere to match the lowest result in the timeslot this fall for “Marvel’s Agents of SHIELD”; and it again fell off in its second half (from a 1.6 at 9 p.m. to a 1.4 at 9:30).

CW aired repeats of Tuesday regulars “The Flash” (0.4/1 in 18-49, 1.6 million viewers overall) and “Arrow” (0.3/1 in 18-49, 1.1 million viewers overall).

Preliminary 18-49 averages for the night: CBS, 2.2/7; ABC and Fox, 1.4/4; NBC, 1.3/4; Univision, 1.2/4; Telemundo, 0.7/2; CW, 0.4/1.

In total viewers: CBS, 15.3 million; ABC, 5.7 million; NBC, 4.2 million; Fox, 3.8 million; Univision, 3.2 million; Telemundo, 1.7 million; CW, 1.4 million.