In their first real head-on battle, NBC's "The Cosby Show" just barely beat the second-season premiere of Fox's "The Simpsons," ratings for the season's big sitcom duel showed Friday.

Cosby's show, which has been trouncing reruns of "The Simpsons" since the season began, had an 18.5 national rating Thursday, just one-tenth of a ratings point higher than the Nielsens for Fox's bug-eyed, big-toothed cartoon clan.In results made public earlier Friday, Fox's show even beat the Cosby comedy in the 24-city overnight ratings race. But both Fox and NBC officials said that a Cosby victory was likely when the national ratings came in.

"We'e very pleased," Peter Chernin, Fox Entertainment Group president, said of the "Simpsons" ratings. "We think it's a good number, a good start for us. It was better than we thought we'd do."

NBC officials also were pleased that The Cos withstood the challenge from the off-the-wall animated sitcom that had been a hit for Fox on Sundays, then was shifted to Thursday nights to take on NBC's long-time ratings champion.

Fox heavily promoted the start of its new "Simpsons" episodes "and gave it its best shot this week," said Preston Beckman, NBC vice president for audience research. "But `Cosby' withstood the onslaught pretty well."

The first half-hour of competing network shows Thursday - a "Columbo" episode on ABC and a movie, "Dark Avenger," on CBS - averaged ratings of 10.6 and 5.4, respectively. Each ratings point represents 931,000 homes.

The ratings for Thursday's "The Simpsons" were nearly double those of the previous week, when a rerun was shown. Cosby's show dropped by a ratings point on Thursday, a comparison with its Oct. 4 ratings showed.

Chernin avoided speculating on whether he thought "The Simpsons" might eventually beat Cosby's show in the ratings.

"We've always said we'd be thrilled to be a strong second, and we still feel that," he said, later adding: "Honestly, I don't know where it's going to go. We're just trying to savor today's happiness and not make predictions."

Whether the two shows will continue to be neck-and-neck in the Nielsens "I really can't say," he insisted. "This is one of the most exciting races in television in several years. Time will tell."