TV Ratings: 'This Is Us' Slides to Series Low

'NCIS' records its largest total audience of the season with the return of a beloved character.
Ron Batzdorff/NBC

NBC's This Is Us recorded its lowest adults 18-49 rating ever Tuesday, though it was still the night's top show in the key ad demographic. 

NCIS, meanwhile, had a season high in total viewers with the return of a beloved character. 

This Is Us scored a 1.7 rating in the 18-49 demo after two weeks off, 0.1 below its previous low in November. Lead-out New Amsterdam held steady with a 1.0, and Ellen's Game of Games (1.5) improved a little on last week, giving NBC a sweep of the demo in primetime.

The return of Cote de Pablo's Ziva to NCIS boosted the CBS show to a season-high 13.24 million viewers while matching the 1.3 in adults 18-49 for its last episode. FBI (1.0) rebounded from a season-low 0.8 for its last outing, and NCIS: New Orleans held at 0.8.

American Housewife (0.9) improved slightly on its Tuesday debut last week on ABC. The Kids Are Alright (0.7) and The Rookie (0.6) each came down a tenth of a point, while Black-ish (0.8) and Splitting Up Together (0.6) were even with their most recent episodes.

Fox's Lethal Weapon (0.7) and The Gifted (0.5) matched their last outings, as did Roswell, New Mexico (0.3) on The CW. The Flash dipped a little to 0.6.

NBC's 1.4 average among adults 18-49 led the night. CBS finished second at 1.0, and ABC (0.7) edged Fox (0.6) for third. The CW, Telemundo and Univision tied at 0.4.