Jimmy Fallon and Jay Leno (Jordan Strauss/JORDAN STRAUSS/INVISION/AP)

NBC, once the king of primetime, morning infotainment, and late-night television, is now an also ran in primetime, and is struggling behind ABC’s “Good Morning America” in the morning. But NBC has managed to hang on to its frontrunner status in late night with Jay Leno, after nearly falling off that throne too, during the seven months it gave Conan O’Brien the keys to the “Tonight Show” kingdom.

Naturally, NBC is now working on another plan to remove Leno from “Tonight.”

This time it’s Jimmy Fallon, who’s warming the bench where Conan once sat, who’s reportedly destined to take over for Leno, when the latter’s contract runs out in fall of ‘14.

This time, however, NBC thinks it knows how to avoid the mistakes it made with Conan, reports NYT’s Bill Carter, who has the inside track, having written the books on late night TV — literally.

The problem, turns out, was geographical.

Fallon won’t be moving to Los Angeles to take over “Tonight Show,” like Conan did. Instead, “Tonight Show” will be moved back to New York, from whence it came, Carter reports. “Tonight” previously was broadcast out of Manhattan from its launch in the mid-50’s, until it was in the midst of its Johnny Carson era.

There’s a sense of urgency to replace Leno since ABC moved relative youngster Jimmy Kimmel to Leno’s 11:35 p.m. timeslot, the fear being that Kimmel will suck up all the younger viewers if Fallon doesn’t move in quick.

Since Kimmel moved to the earlier timeslot in January, Leno has hung on to his lead among 18-49 year old viewers who are the currency of late night TV ad sales. Which does not matter, Leno being old enough to be Fallon’s father.

As the press drumbeat over Leno’s impending exit grew deafening this week, Leno spoke directly to his audience:

 "You know the whole legend of St. Patrick, right? St. Patrick drove all the snakes out of Ireland _ and then they came to the United States and became NBC executives," Leno “joked” during Monday’s monologue.

  NBC’s west-coast chief Bob Greenblatt took umbrage and Leno was asked to knock it off. The late night comic responded the next night with this monologue bit about a Serbian woman with a brain condition that causes her to see everything upside down:

 "Isn't that crazy? It's unbelievable. She sees everything upside down. In fact, she thinks NBC is at the top of the ratings."

 In the most recent issue of GQ magazine, Fallon’s exec producer Lorne Michaels (who also “discovered” Fallon’s “Late Night” predecessor Conan) is quoted as saying Fallon’s takeover of Leno’s show has "an inevitability to it." and that Fallon is “the closest to Carson that I've seen of this generation."