The Buffalo Bills might have a chance to clinch the AFC East on Sunday night when they battle the injury-decimated San Francisco 49ers at Orchard Park, N.Y.Buffalo (9-2) has won six straight games and is on the verge of a fifth straight AFC East crown. If the Miami Dolphins lose to the Green Bay Packers on Thursday night, then the Bills would wrap up the division by defeating the 49ers.Buffalo will be up against a San Francisco squad that may not have quarterback Brock Purdy for the second straight week.Purdy was a limited practice participant on Wednesday with the majority of his workload consisting of handoffs due to his ailing right shoulder.The 49ers (5-6) have lost back-to-back games entering a pivotal contest.Buffalo had a bye last week following an impressive 30-21 home victory over the Kansas City Chiefs.”To be at the bye week … at 9-2 and obviously feeling confident about what we got going on here and the guys that we have in this locker room, it’s a great feeling,” Bills quarterback Josh Allen said.Allen said it’s too early to assume a playoff spot, while Buffalo cornerback Taron Johnson wants to prevent a letdown.”I love where we’re at, but at the same time, we just got to make sure that that we keep that same fire and not get complacent and just continue to play our best ball moving forward,” Johnson said. “So even though we have a good record, we still have things we have to clean up and things we got to get better at.”Buffalo has scored at least 30 points in five consecutive games. Allen has passed for 18 touchdowns against five interceptions this season after throwing a career-worst 18 picks last season.San Francisco got walloped last week without Purdy, falling 38-10 to the host Packers. Brandon Allen started at quarterback and completed 17 of 29 passes for 199 yards with one touchdown pass, one interception and one lost fumble.Allen is 2-8 as an NFL starter. He is again getting heavy work in practice in case Purdy’s shoulder doesn’t significantly improve.The 49ers could use a big performance from running back Christian McCaffrey, who had just 31 yards on 11 carries and caught three passes for 37 yards against Green Bay.McCaffrey missed the first eight games of the season with an Achilles tendon injury and has struggled to run the ball in his three appearances. He has 149 yards on 43 rushes for a paltry 3.5-yard average.