MINNEAPOLIS—Cooper Rush’s first NFL start was a statement victory for the surging Dallas Cowboys with starting quarterback Dak Prescott stuck on the sideline. With every opportunity to outlast the fill-in for the first-place team on the other side, Kirk Cousins and the Minnesota Vikings withered down the stretch. Rush subbed for the injured Prescott and passed for 325 yards and two second-half touchdowns, the last a 5-yard throw to Amari Cooper with 51 seconds left in the Cowboys’ 20–16 victory over the Vikings on Sunday night. “It was just as good as the dream,” Rush said. Rush, the fifth-year backup handed the offense when Prescott was shelved in a game-time decision due to a strained right calf muscle, directed an eight-play, 75-yard drive he finished with a perfect toss to Cooper on a fade in the corner of the end zone. “I was glad everybody got to see that, because …