SO who needs Jack Bauer when butt-kickin’ Sarah Con nor is in the house?

“Terminator: The Sarah Connor Chronicles” premiered to 18.3 million viewers Sunday on Fox – making it the season’s most-watched new show.

Not bad for a series that was forced to replace fan favorite “24” when the writers’ strike knocked Jack Bauer (Kiefer Sutherland) off the air this season.

While “Terminator” was fueled by a terrific lead-in – Big Blue’s 21-17 playoff stunner over the hated Cowboys – it managed to hold on to a chunk of that audience.

And, in doing so, it was the most-watched scripted series debut on broadcast TV in almost two years, since CBS’ “The Unit” in March ’06.

“Terminator” also grabbed stellar numbers in adults 18-49 and adults 18-34, notching the best debuts in those key demos, for a scripted broadcast drama, in three years (“Numb3rs” in Jan. ’05).

The show, based on the “Terminator” movie franchise, stars Lena Headey, Thomas Dekker, Summer Glau and Richard T. Jones.

It moved into its regular timeslot (9 p.m./Ch. 5) last night.