Three weeks into the season, reality shows are hitting the skids.

NBC has yanked the third edition of the competition series "Last Comic Standing" off its Tuesday lineup, effective immediately.

Ironically -- and how appropriate is irony in a story about a show starring stand-up comics -- there was only one episode left to air in this edition's eight-episode order. That, of course, would be the episode in which the winner of the competition is announced.

NBC's move comes just days after Fox pulled the plug on its reality boxing series "The Next Great Champ."

" 'Last Comic Standing' is cancelled!!!" host Jay Mohr says on his Web site.

"Amazing. Why would a network cancel a show with only one episode left?" he adds, which is a good question.

Yesterday, NBC was saying only that the finale would not air next week but that the winner would be revealed to viewers in some fashion or another.

A source with knowledge of the talks said that among the things being considered is an abbreviated finale that would air elsewhere on the NBC schedule or, more likely, on one of NBC's cable networks. An big-winner announcement during the "Father of the Pride" marathon was even being knocked around, though that idea has grown cold, one source said yesterday afternoon.

Ironically -- you just can't have too much irony in this story -- NBC had changed its prime-time lineup to include a fall edition of "Last Comic Standing" based on its performance this past summer.

On his site, Mohr says NBC was not happy with the ratings for the third edition and decided to pull the plug. It's true, the ratings were really, really bad. A perfectly adequate summer series -- the second edition averaged about 8 million viewers -- "Comic" opened its "fall" edition in late August with 7.7 million viewers, following a special 90-minute edition of "Fear Factor." It hasn't seen that many viewers since. Most recently, it scored 5.7 million; last week it suffered a series low of 5.5 million.

Even worse, from NBC's point of view, this past Tuesday, "Last Comic Standing" finished fifth in its time slot among the 18-to-49-year-olds NBC says it does all its ad sales off of. Yes, "Comic" came in behind ABC's sitcoms, Fox's baseball playoffs, WB's "Gilmore Girls" and even CBS's military drama "NCIS" among those viewers, and it didn't beat UPN's sitcoms by much. "Comic" can't be blamed entirely, but it contributed to NBC's third-place finish last week in the demographic. NBC is also third this season to date, down 15 percent compared with the same point last season.

Still, to the extent that TV industry executives care about "Last Comic Standing" -- which is to say not much -- they puzzled yesterday over why NBC would pull the very last, payoff episode out of a non-sweeps week. Why not just run the last episode so as not to infuriate the show's loyal, albeit small, core audience?

Instead, NBC will air a 90-minute marathon of "Father of the Pride" from 8 to 9:30 p.m. next Tuesday. That's right, three back-to-back episodes of the animated series that NBC said it scheduled at 9 rather than 8 p.m. to send a message to parents that it was not a program for children.

More than one non-NBC exec speculated yesterday that the decision to scrub the last "Comic" episode may have something to do with the schedule for "Father of the Pride" and NBC's recent postponement of "The Contender," both of which are produced by Jeffrey Katzenberg at DreamWorks SKG.

NBC announced this week that it would unveil its boxing competition series in January. The network had been expected to premiere the series, from reality hotshot Mark Burnett, in November, which is a sweeps month. But that was before Fox debuted its rip-off boxing series "The Next Great Champ" in early September and it tanked in the ratings because, hello, not many people care about boxing. Fox will burn off the remaining episodes of "Champ" on Fox Sports Network.

Even so, NBC's decision to delay the debut of "Contender" may have been troubling to Katzenberg, speculated those industry executives who love a good conspiracy theory -- and who doesn't love a good conspiracy theory -- particularly while his "Father of the Pride" is doing such sickly numbers on Tuesday night with the anemic "Last Comic Standing" lead-in.

Maybe, they theorized, this was NBC's way of making nice, and it can't hurt to yank "Comic" if NBC needs to see quickly what "Pride" can do with a stronger lead-in before ordering more episodes of the cartoon series.

The punch-out line: NBC canceled host Jay Mohr's series with one episode left.