The The Associated Press

NEW YORK - For a fourth-place network that hasn't been a threat to anyone but itself the past few years, NBC sure drew a lot of negative attention from its rivals when new fall prime-time schedules were revealed.

Maybe they're actually worried.

NBC's decision to air a Jay Leno comedy hour every weeknight at 10 o'clock overshadows anything else broadcasters are planning for the fall. It could be an ingenious move, or it could give CBS and ABC a better chance at establishing scripted shows in that hour and bury NBC deeper.

Jimmy Kimmel, speaking during ABC's presentation to advertisers, said that NBC wouldn't let Leno jump ship “even if they had to destroy their entire network.” Dawn Ostroff, entertainment president of the tiny CW network, reminded advertisers that it had as much scripted programming as NBC.

CBS Corp. chief executive Leslie Moonves, as he often has, really knew how to stick the knife in.

“There's a difference between the (broadcast TV) model being broken,” he said, “and not being able to find any new hit shows for years.”

NBC is already warning that the Leno move can't be measured like most new fall shows, when two or three weeks make all the difference. Take into account what Leno does all year, particularly when the other networks are showing repeats, said NBC Universal chief executive Jeff Zucker. Because Leno's show will be much cheaper to produce than scripted dramas, it doesn't necessarily have to win in the ratings to be a financial hit.

“I understand why our opponents are saying what they are,” Zucker said. “I get it. What about the chance that it might work?”

Leno may put on the quintessential “aw shucks” demeanor, but he doesn't deny the competitive challenge.

“That's what gives you the impetus to go out and do what you do,” he told reporters. “To prove people wrong.”