The Flash” opened its fourth season on Tuesday down in both key measures from the Season 3 premiere, according to Nielsen overnight data.

Airing at 8 p.m. on The CW, “The Flash” averaged a 1.0 rating in adults 18-49 and 2.8 million total viewers. That is down approximately 20 percent in the demo and 10 percent in total viewers compared  to the Season 3 premiere (1.3, 3.2 million). At 9, the Season 3 premiere of “Legends of Tomorrow” (0.6, 1.7 million) was even with the Season 2 premiere.

On NBC, “The Voice” (2.3, 10.9 million) was even at 8, as was “This Is Us” (2.8, 10.9 million) at 9 and “Law & Order True Crime: The Menendez Murders” (1.1, 4.9 million) at 10.

For CBS, “NCIS” (1.4, 13.3 million) and “Bull” (1.2, 11.1 million) were even. “NCIS: New Orleans” (1.1, 9.5 million) was up slightly in the key demo.

On ABC, “The Middle” (1.4, 5.8 million) was down slightly in the demo, as were “Fresh Off the Boat” (1.1, 4.1 million) and “Black-ish” (1.3, 4.5 million). Both “The Mayor” (1.0, 3.4 million) and “Kevin Probably Saves the World” (0.8, 3.6 million) were down in both measures.

For Fox, “Lethal Weapon” (0.9, 3.8 million) hit a new series low in both measures. “The Mick” (0.7, 2.3 million) was down in the demo, while “Brooklyn Nine-Nine” (0.7, 1.8 million) was up.

NBC won the night in the demo with a 2.1 but finished second in total viewers with 8.9 million. CBS was second in the demo with a 1.2 but first in total viewers with 11.3 million. ABC was third overall with a 1.1 and 4.2 million. Fox and The CW tied for fourth in the demo with a 0.8. Fox was fourth in total viewers with 2.9 million. The CW was fifth in total viewers with 2.3 million.