They brought the Buffalo Bills back for a curtain call today. They screamed, cheered and chanted, most of the 77,133 fans in Rich Stadium. Nick Mike-Mayer, the place-kicker, waved and laughed. His coach, Chuck Knox, cried for joy.

And then Mike-Mayer and Knox retreated into the tunnel and breathed huge sighs of relief.

Mike-Mayer's 30-yard field goal 5:14 into sudden death overtime gave the Bills a dramatic 10-7 victory over the Los Angeles Rams, virtually sealing a playoff bid for Buffalo and all but assuring that the Rams (9-5) will lose the NFC West for the first time in eight seasons.

But, even after winning, the Bills, now 10-4 and leading the AFC East by 1 1/2 games over New England, which will play Miami Monday, had to wonder how they had let so many chances slip away before they finally put the crippled Rams away.

"It got to the point," said Buffalo quarterback Ferguson, "where I wondered just how we were going to win the football game."

In all, the Bills' offense produced three points, the ones that won the game. Safety Steve Freeman came up with the Buffalo touchdown, intercepting one of Pat Haden's passes and returning it 47 yards 2:54 after intermission.

The Rams answered that score with their only drive of the day, 80 yards in 13 plays, plus one key penalty. Mike Guman's three-yard touchdown run with 1:36 left in the third capped the drive. Other than that, and a missed 30-yard field goal by Frank Corral, they never threatened. Meanwhile, Buffalo's offense had many chances but still came up empty.

Consider that Mike-Mayer missed two 38-yard field-goal attempts and that the Bills were stopped twice on fourth and one, first at the one, then at the eight. Then, Joe Cribbs fumbled away the ball at the Ram 11 with 1:08 left in regulation.

The Rams lost quarterback Vince Ferragamo in the second quarter when Ben Williams' helmet slammed against the quarterback's ribs, and they lost leading rusher Elvis Peacock with a twisted knee, so they couldn't move after the Cribbs fumble, sending the game into overtime.

"I was hoping I'd get a chance to win it in the overtime," Mike-Mayer said. "I won one in overtime against New England last year and I still had confidence in myself, even though I had had a miserable day. I wanted a chance."

The Rams couldn't move after the kickoff and punted. Buffalo took over at its 34.Cribbs, who finished with 83 yards on 26 carries, giving him 1,000 for his rookie season, picked up 12 on three carries. Then, Ferguson got another first down with a quick pass to Roland Hooks at the Ram 42.

On second and 10, a scrambling Ferguson, slipping on the wet artificial surface, lofted a wobbly pass toward Frank Lewis. Ram rookie cornerback LeRoy Irvin, thinking interception, dashed toward the ball. He got one hand on it. But Lewis, also coming back to meet the ball, yanked it loose, took possession of it, spun free of Irvin's diving tackle at the 23 and got to the 13.

The crowd, which had sat through mist, fog and rain in a relatively balmy (45 degrees) day, was screaming. Knox wasn't waiting around for any fumbles this time. He sent in Mike-Mayer.

"We had fumbled the ball down there before and I didn't want to take any chances," said Knox, who coached the Rams five years before coming here in 1978. "If we had a malfunction on the snap, we'd just eat the ball and try it again."

Grant's snap was high. But David Humm got the ball down and Mike-Mayer hit it solidly.

"Just a helluva win," said a very emotional Knox, who had Ferguson run out of a shotgun to offset the Rams' eight-man front; who ran his offense without a huddle to prevent L.A.'s defensive substituting at times; who was, in his quarterback's words, "out of character a lot today."

"The word was out early this week," said offensive guard Reggie McKenzie.

"The man wanted this one in the worst way. We gave him the game ball."

Haden, a starter under Knox, but the backup to Ferragamo under Coach Ray Malavasi, walked across the hall after dressing to congratulate Knox. Said Haden: "Coming in cold off the bench is no excuse; that's my role here now and they pay me a whole lot of money for it. I didn't get it done today." n

The Bills finally did, but only after torturing their fans, who last saw a Buffalo team in the playoffs in 1974.

"Going back out, hearing those fans was such a great feeling," Mike-Mayer said, almost smiling under his mustache. "I felt I had let them down before. sI was glad Chuck still had faith in me and when I finally came through, I was really elated."