No fewer than four broadcast series sank to all-time lows or season lows Tuesday night, based on Nielsen overnights for the key 18-49 demo.

TVbytheNumbers.com reports that CBS’s "Big Brother" and NBC’s "Betty White’s Off Their Rockers" both set series lows, while NBC’s "America’s Got Talent" and ABC’s "Extreme Weight Loss" reached season lows in the demo.

But even with "America’s Got Talent’s" erosion — slipping three-tenths from last week’s season low to a new season low of 2.3 in viewers 18-49 — NBC won the night, as "Talent" still finished as the top show of the night on broadcast.

NBC opened prime time with back-to-back episodes of "Betty White’s Off Their Rockers" — a repeat at 8 p.m. followed by an original at 8:30 — with both installments delivering 0.8 averages in 18-49. The fresh episode was down two-tenths from a week ago.

CBS’s "Big Brother" fell to an all-time low for the series, losing four-tenths from last week’s Wednesday premiere to average a 1.8 in adults 18-49. The rest of the CBS prime-time lineup was repeats.

ABC saw its two-hour "Extreme Weight Loss" sink to a season low with a 1.0 in 18-49, losing two-tenths from a week ago. Leading out from it, a "Body of Proof" repeat delivered a 0.6.

Fox was down too, with its two-hour "So You Think You Can Dance" settling for a 1.5 average in the 18-49 demo, down two-tenths from a week ago.

NBC came out on top for prime time overall with a 1.8 average rating in viewers 18-49, ahead of Fox (1.5 average), Univision (1.4), CBS (1.2) and ABC (0.9). NBC claimed the top spot in total viewers as well, averaging 7.4 million to lead CBS (6.0 million), Fox (4.3 million), Univision (3.7 million) and ABC (3.3 million).