Cincinnati is one victory away from the Super Bowl and Buffalo's season is over because of a seldom used Bengal running back who had the best day of his pro career, a delay-of-game penalty and a Bill pass that was inches away from being caught for a touchdown.

That's about all that separated the teams after Cincinnati's struggling 28-21 success in this American Football Conference semifinal that set up the AFC championship game at 1 p.m. here next Sunday against the San Diego Chargers.

No matter how close the outcome, it made the Bengals an ecstatic group. Their first playoff victory in four tries, it was even more special considering virtually the same team finished 6-10 in 1980 before compiling a 12-4 record this year.

"This one is really, really sweet," said linebacker Jim LeClair, who had seen Cincinnati lose 34 of its last 48 games prior to this season. "About eight or nine of us have been through the real pits here and no one expected us to be this good this year. Now look how close we are to the Super Bowl."

Yet this was not a typical 1981 Cincinnati triumph. The Bengals' high-octane offense was toned down considerably, especially after Buffalo's generosity led to an early 14-0 Cincinnati lead. Quarterback Ken Anderson, a 328-yard passer in a 27-24 overtime conquest of Buffalo early this season, tossed only 21 passes today, completing 14 for 192 yards. For the most part, Cincinnati was content to try to nurse its early advantage.

The Bengals decided to run more and pass less when halfback Charles Alexander, who couldn't even outrush Anderson this year, capitalized on Buffalo's decision to key on fullback Pete Johnson. Alexander gained a season-high 72 yards on 13 attempts, including touchdown sorties of four and 20 yards. Before today, Alexander had only 98 carries.

Alexander's work enabled the Bengals to play an almost errorless game.

Still, Buffalo was very much in it with three minutes to play, only to be hurt by the delay penalty and the errant pass.

The penalty came with 2:58 left, the Bills' 28-21 deficit the result of a 16-yard touchdown pass from Anderson to Cris Collinsworth with 10:39 to play. The Bills drove to the Cincinnati 20, where they faced fourth and three. After a timeout, quarterback Joe Ferguson found receiver Lou Piccone for a first down at the 15, but the gain was wiped out; the 30-second clock had expired before the snap.

"They were trying to sneak in two extra wide receivers," Cincinnati safety Mike Fuller said. "They waited until maybe 13 seconds were left (to get the play under way) and I thought they made it work. We had only four defensive backs in the game so they got one-on-one coverage. It was cutting it pretty close for us."

Although Coach Chuck Knox gestured vehemently about the call on the sidelines, Ferguson didn't argue.

Now Buffalo, its two starting running backs out injured, had to overcome fourth and eight from the 25. Instead of going for the first down, Ferguson threw deep to halfback Roland Hooks, who had beaten his linebacker coverage down the middle of the field.

The ball barely eluded the diving Hooks at the back of the end zone. Cincinnati took over and Buffalo never had another chance.

"I knew I had to throw the pass long over the linebackers because they dropped real deep," said Ferguson, who recovered from a horrible start (none for five, one interception) to pass for 202 yards.

"I was surprised we didn't throw more," Cincinnati's Collinsworth said. "I came in at halftime and realized I hadn't caught a pass and I started to get down on myself. But I said, 'They haven't thrown one your way yet. We're winning (14-7) and they know what they are doing.' "

Perhaps things came too easily too quickly for Cincinnati, grown accustomed to such lopsided victories this season as a 40-17 trouncing of the Chargers in San Diego two months ago.

A 27-yard punt return by Fuller to the Bill 42 set up Alexander's first score on the Bengals' first possession.

Next, veteran cornerback Ken Riley intercepted off Ferguson and returned to the Buffalo 48. Anderson completed passes of 14 and 22 yards before Johnson, the Bengals' 1,000-yard rusher, plowed over from the one for a 14-0 lead with 2:40 to go in the quarter.

The Bengals blew a chance to be even further ahead on their next possession. Two Anderson completions had the ball at the Buffalo 15, but a sack and a block of Jim Breech's 33-yard field-goal try gave the Bills a much needed lift.

An interception stopped one Buffalo threat but Ferguson came back from that with a fine 55-yard pass to Jerry Butler that led to Joe Cribbs' one-yard touchdown run with 20 seconds remaining in the half. Cribbs struck again early in the third quarter, breaking around left end for a 40-yard touchdown and a 14-14 tie.

Although it became 21-21 when a Ferguson strike to Jerry Butler matched Alexander's 20-yard run, the Bills now were working under a handicap. Cribbs' knee was bruised when he was tackled at the end of the long run and soon was out of the game for good after gaining 90 yards. Then fullback Roosevelt Leaks left with a pinched nerve in his neck.

Cincinnati recaptured the lead again in the fourth quarter, two Anderson passes playing key roles, a 42-yarder to Steve Kreider and three plays later the game-winner to a wide-open Collinsworth.

On third and one from the Bengal 34, "we were having trouble running on short yardage," Anderson related, "so we decided to pass." The play to reserve receiver Kreider was put in especially for this game, and just such a third-down situation. Kreider made it more than the Bengals bargained for; he caught the little delay toss four yards down the field and turned it into a big gain by eluding two tacklers and running down the sideline.