Buffalo's four sacks in a 20-3 win over the Denver Broncos on Sunday that has the Bills off to their best start in 23 years.
John Brown made a diving 34-yard touchdown catch, and Cole Beasley scored on an 18-yard reception. Allen finished 15 of 25 for 185 yards and threw his first interception in 172 attempts.
Frank Gore had 65 yards rushing to up his total to 15,289 and move ahead of boyhood idol Barry Sanders into third on the NFL career list. The 15-year veteran also increased his total to 19,154 yards from scrimmage to pass Marshall Faulk for fourth on the list.
Rookie Ed Oliver and Star Lotulelei had a sack apiece, while cornerback Tre'Davious White snuffed out a potential scoring drive by intercepting Brandon Allen at the Buffalo 8 in the final minute of the first half.
Buffalo improved to 8-3, to match its best start since Hall of Fame quarterback Jim Kelly's final season in 1996, while keeping the Bills firmly in position to secure their second playoff berth in three years.
The Broncos dropped to 3-8 in Vic Fangio's first season as coach, and for the second time in three years. And it might be time for Fangio to look to the future after quarterback Brandon Allen went 3 of 14 for 4 yards in the second half and finished 10 of 25 for 82 yards passing with an interception.
Brandon Allen dropped to 1-2 in three starts after Joe Flacco sustained a season-ending neck injury. And Allen's replacement is already waiting in the wings.
Rookie second-round draft pick Drew Lock has spent the past two weeks practicing since being sidelined in August by an injury to his right thumb.
Last week, Fangio said he wasn't any closer to targeting a possible return date for Lock, who would remain on IR the rest of the season if he's not activated by Dec. 3. Activating Lock would at least provide some substance to what's become a lost season for a team that was coming off a 27-23 loss at Minnesota in which the Broncos squandered a 20-0 lead.
A week after managing a season-best 394 yards against the Vikings, the Broncos managed just 134 yards and nine first downs against the Bills.
This was an important win for Buffalo, which now enters the toughest stretch of its season.
Starting with a game at Dallas on Thursday, the Bills' next four opponents entered this week with a combined record of 28-12. This come after Buffalo built its 8-3 record by beating many of the NFL's pushovers. The Bills' previous seven wins — including two against Miami — came against teams that entered this week with a combined 15-55 record.
Buffalo led from the start after settling for field goals on its first two drives. Stephen Hauschka capped a 17-play, 69-yard drive with a 39-yard field goal to open the scoring. And then he hit a 23-yard chip shot to cap a 12-play, 87-yard drive.
Buffalo then broke the game open when Allen capped the opening drive of the third quarter with an 18-yard touchdown pass to Cole Beasley to put the Bills ahead 13-0.