In past years, Fox’s pact to air post-season baseball games was an albatross to the network : Ratings were decent, sometimes better, but the cost was a delayed start to its fall lineup that let rivals gain an advantage.

This year, it’s a different story. Ratings for thrilling playoff games spiked 60% ahead of last year, and other networks’ new schedules have largely met with yawns from viewers.

Tonight, ahead of Tuesday’s third World Series game, Fox begins the belated unveiling of its fall lineup with the return of last season’s No. 2 show - the not-really Joe Millionaire- and Skin, a soap set against a porn-industry backdrop from producer Jerry Bruckheimer.

Fox’s promo mavens have spared no opportunity to burn those shows, and others returning next week, into the consciousness of 25 million playoff watchers.

There’s no guarantee that the tactic will boost viewership of Fox’s entertainment series. Sports fans tend to be a bit older and more heavily male than the typical prime-time viewer, and they watch fewer sitcoms and dramas. "The truckload of 45-year-old men is not suddenly going to be tuning into That ’70s Show," media buyer MindShare analyst David Marans says.

But, as they say, the added exposure couldn’t hurt. "Anytime you are getting a circulation the size they’re getting, it’s an advantage," NBC promo chief John Miller says.

But even before the World Series began Saturday, the games did accomplish one objective : They have unexpectedly given Fox a narrow lead this season among the valuable audience of adults ages 18 to 49, giving Fox a better chance of stealing the season-long crown from NBC.

And with viewers starved for some sign of a water-cooler hit, it’s unclear whether Fox now stands a better chance of getting attention or risks facing the same indifference.

Initiative Media analyst Stacey Lynn Koerner is optimistic. "When they launch their schedule, it’s just going to energize the broadcast lineup, and they’ll get credit for it," she says, predicting that American Idol - returning in January - will make for a razor-thin race against NBC among young adults.

Last year, Fox trotted out new and returning shows on four nights in mid-September, only to yank them a few weeks later for baseball. They returned but never recovered : Viewers didn’t especially like Firefly, Fastlane or John Doe, but those who did had a tougher time finding them. The network had an especially weak fall, only to recover with Idol in January.

"We had put a lot of promotion behind certain shows and had kind of shot our wad, so to speak," says Fox Entertainment chief Gail Berman. "And then we had to bring them all back again."

This fall, Fox launched only its Friday and Saturday lineups but wisely chose August to begin a seven-week trial run of The O.C., a teen soap that quickly caught on with Fox’s core audience, grew from week to week and helped win back women who lately have turned to the network mostly for reality programs. The series has been extended to 27 episodes this season.

The news is not so good on Fridays : The lineup of Wanda at Large, Boston Public and new Latino sitcom Luis already has tanked and is unlikely to return intact. And The Ortegas was benched even before its scheduled premiere next week, continuing a long Fox tradition of bailing on shows it already has touted. Bernie Mac will move into the post-Simpsons time slot instead on Nov. 9.

At least for the short term, Fox’s momentum will ride in large part on the success of Joe Millionaire, which averaged 23 million viewers last winter and was the season’s top series among young adults. It will air twice a week during the November sweeps period, and as the lead-in to Skin on Mondays and 24 on Tuesdays, it probably will boost the audience for both shows.

Though Joe won’t likely remain as popular, "if we do half of what we did last year, it would be very satisfying," Berman says.