Just one night after one of its series sank to an all-time low in the ratings, CBS suffered the same fate with another show Monday night, based on Nielsen overnights for the key 18-49 demo.

TVbytheNumbers.com reports that CBS’s summer hit "Under the Dome" fell to a series-low 2.5 average rating in viewers 18-49, losing 11% from its number a week earlier.

The report cites "both CBS’s ongoing carriage dispute with Time Warner, which has left TWC customers in Los Angeles, New York City and Dallas without CBS, and unusual competition from what was billed as the most dramatic ‘Bachelorette’ finale ever" as possible explanations for "Dome’s" slide.

The result came one night after an all-time low for CBS’s "Unforgettable," which faced competition from the return of NBC’s Sunday night football coverage — albeit a preseason game.

About that "Bachelorette" finale on ABC, it may have been dramatic but it was the show’s lowest-rated season finale in its history, managing just a 2.5 average in the 18-49 demo — off 16% from the previous season finale. Still, it was up 8% from last week, and a season high.

ABC’s wrap-up show "The Bachelorette: After the Final Rose" matched its lowest rating in series history with a 2.5 average in 18-49 — down 19% from a year ago. The "Bachelorette" programming still gave ABC enough of an audience to easily win the night.

NBC had its own problems. "American Ninja Warrior" turned in its lowest 18-49 number of the season, a 1.4 average rating, down 7% from last week, and "Siberia" equaled last week’s all-time low with a 0.7. The bright spot was "Get Out Alive With Bear Grylls," which improved 8% after a season low a week ago, registering a 1.3.

Fox aired an all-repeat lineup, while CBS aired two hours of repeats before rolling out its fresh "Under the Dome."

On a night of season lows and series lows, the number of the night may have to go to CW’s "Breaking Pointe," which barely moved the needle, delivering a season-low 0.1 average rating in viewers 18-49, down 50% from the show’s 0.2 a week earlier.

For prime time overall, ABC was the easy winner in viewers 18-49 with an average rating of 2.6, ahead of CBS (1.6), Univision (1.2), NBC (1.1), Fox (0.7) and CW (0.2). CBS put up a little more of a fight in total viewers, but it still went to ABC with 8.7 million, topping CBS’s 6.3 million, NBC’s 3.5 million, Univision’s 3.1 million, Fox’s 1.8 million and CW’s 564,000.