With just days to go before media buyers plunge into negotiations for nearly $9 billion in broadcast ad inventory for the coming year, there's been a shakeup in the outlook for spending.

After previewing the networks’ fall schedules last week, buyers have been constructing ratings projections, and now it looks as though ABC will pull ahead of CBS in the amount of inventory it sells in the broadcast upfront when it breaks, perhaps as early as late next week.

Initially, forecasters had figured CBS to lead in upfront ad sales, at about $2.2 billion, with ABC trailing by some $100 million.

Now media researchers believe ABC will slide ahead, based on a week of playing and replaying previews of each network’s new programs. NBC will come in third and Fox, which airs fewer primetime shows and thus has less inventory to sell, will come in fourth.

Further, based on its fall lineup, most media researchers are predicting that ABC will challenge Fox for No. 1 in the 18-49 demographic next season.

This is so even though ABC is introducing a slew of new shows, 10 in all, which makes predicting how it will do that much harder. Researchers believe the network can still pull it off nurturing those new shows by pairing them with strong existing performers.

“ABC is relying on some of their proven shows. Their theme is building off successful nights to build new shows," says Francois Lee, vice president of video investment and activation at MediaVest.

Whether ABC takes the season will come down to two things: how well that strategy succeeds, and in particular whether  “Private Practice," the much-anticipated spinoff of “Grey’s Anatomy,” becomes a hit, but also how well Fox's "American Idol" performs, after sliding in the ratings this season.

“If ‘Idol’ stays strong, Fox will win,” says Lisa Quan, vice president and director of audience analysis at Magna Global. “If not, ABC has a chance and so does CBS. NBC is too far out of the picture at this time.”

Upfront forecasts have not changed for NBC and Fox following last week's upfront previews. Merrill Lynch analyst Jessica Reif Cohen has been projecting $1.8 billion for Fox, slightly behind NBC’s $1.9 billion.

Still, NBC is looking iffy. Buyers were not particularly impressed by its fall lineup, and most researchers now think it’ll take a few more years for the network to pull out of fourth place in the ratings. That's so even though buyers like some of its new shows, including the drama “Chuck,” about a secret agent, and midseason drama “Lipstick Jungle.”

“NBC looks like it could do worse than my previously published estimates,” says David Joyce, an analyst with Miller Tabak & Co. “It’s too sci-fi, fantasy-oriented, which is more of a target for young males, which is the precise demographic that has been leaving TV for videogames and online media.”

NBC will also suffer because of its Thursday lineup. It now trails both ABC and CBS on a night it once dominated.

Some buyers estimate that Thursday accounts for more than one-third of upfront revenue.

NBC’s schedule is unchanged on the night while ABC will continue to dominate with “Grey’s” and CBS is beefing up its schedule by bringing “Without A Trace” back from Sunday.

Meanwhile, the CW impressed many buyers with a lineup most say is stronger than it was this year, its rookie season.

“Even though I had brought down [my forecast] for the CW as they were losing ‘Gilmore Girls,’ ‘Veronica Mars,’ etc., they have had a good reception for their new shows,” says Joyce.

Even so, some forecasters have been revising down the outlook for upfront spending based on the ongoing slide in ratings, which means just that much less inventory to sell. Each network is down from last season in the 18-49 demographic and that trend is expected to continue.

Joyce recently lowered his upfront forecast from a 4.7 percent increase to 3.5 percent.

But Merrill Lynch’s Cohen last week held to an earlier prediction for an increase in low- to mid-single-digit percentages, to $8.7 billion. Media Life readers, in a recent poll, are forecasting spending to grow between 1 percent and 3 percent over last year's upfront market.

“The currency is changing, so it’ll be difficult to compare ratings year to year,” says Magna’s Lisa Quan, referring to Nielsen Media Research’s DVR and average-commercial-minute ratings. “But I don’t think ratings will be going up.”