Even as CBS cuts deeper and deeper into NBC's Thursday dominance, regularly finishing No. 1 in households and total viewers, NBC has succeeded in holding onto the demographic that matters most to advertisers, adults 18-49, with its original programming.
   NBC has finished No. 1 on Thursday nights with original programming since 1987, when Nielsen first introduced the people meter.
   That is, up until last week.
   CBS can thank Fox and the hotly contested World Series for pulling away just enough 18-49 viewers to give it its first win ever against an NBC Thursday night lineup of original shows.
    One has to think it won’t be the last, with “Friends” fading, “Scrubs” struggling, and “Coupling” essentially DOA.
    To be sure, CBS’s victory was a slim one. Its 7.5 nightly average was a mere .1 ahead of NBC. 
    NBC’s three-week average for Thursdays with original episodes up until last Thursday had been a 9.2, but it was a declining average from a 10.4 in debut week. 
   CBS, on the other hand, has stayed quite steady at a 7.46 Thursday average, fluctuating just .4 in four weeks.
    In addition to Game 6 of the World Series, which garnered a 6.5 rating, CBS also benefited from the stumbling "Coupling," which sank to a series-low 4.9, retaining just 73 percent of lead-in “Will & Grace’s” audience.
   Without “Coupling,” NBC would have maintained its No. 1 Thursday standing with about a 7.7 adults 18-49 average.
   But “Coupling” isn’t NBC's  only Thursday problem.
   “Scrubs” lost 25 percent of lead-in “Friends’” audience last week, and even “Friends” is showing signs of decay with its lowest 18-49 rating of the season.
   Again, blame baseball in part, but it’s still a dramatic trend. Last week’s 9.1 “Friends” rating was off 23 percent from its season premiere and down 17 percent from its season average of 10.9.
   If the show continues to dip, it could clear the way for CBS’s “Survivor,” which always gets a big boost at 8:30 p.m., to pull ahead for the entire hour. And that would mean more Thursday wins for CBS, which already owns the 9 p.m. hour with “CSI.”
   NBC’s Thursday loss was surprising, but the pulseless debut for Fox’s “The Next Joe Millionaire” Monday at 8 p.m. was last week's real shocker.
   Media buyers had predicted in Media Life last week that the numbers could be off 5 to 20 percent from last year. They were being generous.
   Instead the show averaged less than a third of its 10.1 adults 18-49 debut last January with a 3.2. Its total audience was less than half of last year’s.
   The second episode this week dipped even more, to a 2.5 adults 18-49 rating, meaning that Fox’s November sweeps strategy of airing a second “Joe” episode on Tuesdays leaves it with problems on two nights it expected to be strong.
    Expect schedule shifts soon. 
    Monday’s 9 p.m. “Skin” will have to either move somewhere else or receive a stronger lead-in. Fox already has begun moving things on Fridays, where it canceled “Luis” this week.