Josh Allen’s 26-yard touchdown run on fourth-and-2 with just more than two minutes left sealed the Buffalo Bills’ 30-21 win Sunday and dealt the visiting Kansas City Chiefs their first loss of the season.Facing the choice of attempting a short field goal or handing the defending Super Bowl champions and quarterback Patrick Mahomes the ball and time to drive for a win, Bills coach Sean McDermott turned the game over to Allen, who first looked to pass, then diced through a Chiefs defense that is among the league’s best against the run.The Bills improved to 9-2. The Chiefs fell to 9-1.Allen completed 27 of 40 passes for 262 yards and led the Bills (9-2) with 55 rush yards.Buffalo appeared to take control by dominating the time of possession in the second half, a category the Chiefs have controlled.With the Bills defense containing Mahomes, Allen bloomed in the fourth quarter. His 12-yard pass to wideout Curtis Samuel with 12:51 left paid off a 10-play, 83-yard drive that took six minutes off the clock and gave the Bills a 23-14 lead.But Mahomes led the Chiefs 70 yards in 4:58 to trim the lead to 23-21 on his second touchdown pass — a 1-yarder — pass to tight end Noah Gray.Buffalo has won six straight this season and the last four regular-season games in the series. The eventual Super Bowl champion Chiefs eliminated the Bills in the divisional round of the playoffs in Buffalo in January, however.