With Fox's cancellation of the new drama "Skin" yesterday, the network needs to move quickly to rebuild its Monday schedule.

   After an unexpectedly strong start to the season with the baseball playoffs, Fox is limping into the November sweeps with a weaker lineup of new shows than even floundering NBC. 
   That put Fox way behind to start sweeps, tying for third with ABC last week among 18-49s in a demographic it was supposed to challenge for the season lead in.

   Fox has problems on every weeknight, but the one that needs the most attention is Monday, a night that was expected to be among its strongest. 
   Here's what Fox needs to do to rebuild it.

   Start by bringing “Boston Public,” a decent performer last year at 8 p.m., back from its Friday exile, where it has been averaging less than a 2.0 18-49 rating.

   Then move summer hit “The O.C.,” whose audience showed last week that it was willing to follow it to any night, to the 9 p.m. slot when ABC’s “Monday Night Football” is over.

    That’s a less competitive slot than “The O.C.’s” current Wednesday at 9 p.m., where it faces ABC’s “The Bachelor,” NBC’s “West Wing,” CBS’s “King of Queens” and the WB’s “Angel.”

   The teen and 18-34 crowd that “The O.C.” targets doesn’t much care for other Monday 9 p.m. fare, such as CBS’s “Everybody Loves Raymond” or NBC’s slightly older skewing “Las Vegas.”
   Once "American Idol" returns on Wednesdays, the audience for the 8:30 show will stick around for anything Fox airs at 9, so why waste a hit that can stand on its own in that slot?

   As it is “The O.C.” will get double exposure starting this week, when Fox will replace the “Skin” reruns it planned to show on Thursdays at 9 p.m. with encore “O.C.” shows.

   Monday has also made Tuesday into a problem, as Fox had to yank the “Joe” replays that were supposed to air at 8 p.m. and replace them with reruns of other shows. 

   Meanwhile, in last week's start to the November sweeps, NBC finished first among 18-49s on the first three nights of sweeps, with Fox taking Sunday night. That helped NBC to one of its largest margins of victory of the season, averaging a 4.4 that was 18 percent ahead of second-place CBS’s 3.6.

   Still, NBC was off 8 percent from its 18-49 average during the same week last year. Both NBC and CBS are down 12 percent in the demographic from their season-to-date average last year. ABC is down 5 percent.

   Fox is up 12 percent thanks to much better baseball ratings this year than last, and actually leads among the networks in year-to-date 18-49 average with a 4.5.