The Washington Post’s mike Jones breaks down the Redksins’ win over the Dallas Cowboys last night for the team’s first division title since the 1999 season. (The Washington Post)

On a night when quarterback Robert Griffin III lacked his usual precision on some passes and the customary explosiveness on his runs, the Washington Redskins turned to their other star rookie. And running back Alfred Morris delivered, barreling his way to a 28-18 victory, the Redskins’ first NFC East title since 1999, and two franchise records.

Every bit the workhorse back that he has been this season, Morris, who had carried the ball on 63 percent of Washington’s running plays this season as the game began, gashed the Cowboys for 200 yards and three touchdowns on 33 carries — all career highs.

“I knew in order for us to win, we’d have to get the ground attack going, so I came out here to give it my all, regardless,” said Morris, whose production on the ground was well more than half the Redskins 361 yards of offense. “It just turned out to be my best game thus far, and I’m just thankful we were able to get into this postseason.”

Morris entered the game with a chance to break two individual franchise records. He needed 104 yards to surpass Clinton Portis’s single-season rushing record of 1,516 yards, set in 2005. And he needed a score to break Charley Taylor’s 48-year-old mark of ten touchdowns by a rookie.

The 5-foot-9, 219-pound Florida Atlantic product surpassed each milestone with apparent ease, and ended the night with 1,613 yards and 13 touchdowns.

Late in the second quarter, Morris raced 17 yards into the end zone to pick up his 11th touchdown of the year. (Taylor rushed for five touchdowns and caught five more touchdowns as a rookie.)

Early in the third quarter, Morris surpassed Portis with a 10-yard run that gave him 1,523 rushing yards on the season.

“He was a beast,” rookie cornerback Richard Crawford said of Morris. “I always knew he could do it. I can’t speak enough about it. It speaks for itself. He runs hard. Old-fashioned running back. A ’90s running back playing in 2012. Great back.”

More important than the records, however, was the fact that Morris’s production ensured success for Washington on a night when its passing game sputtered for the better part of three quarters.

Playing in his second game back since spraining the lateral collateral ligament in his right knee, Griffin struggled with accuracy throughout the first half. In the first two quarters combined, the rookie of the year candidate — previously one of the most accurate passers in the league — completed five of 11 pass attempts for just 43 yards. At halftime, Griffin had a quarterback rating of 56.2, well below his season mark of 104.1 (second-best in the league entering the game). At halftime, Morris was Washington’s leading pass-catcher with two receptions for 12 yards.

With the passing game languishing, offensive coordinator Kyle Shanahan fed Morris the ball often, and Dallas’s battered defensive front — which was missing starting nose tackle Jay Ratliff, who was out with an injury — had no answer.

“The guy that separated himself from the pack today was Alfred,” Redskins Coach Mike Shanahan said of Morris, who entered the game as the fourth-leading rusher in the league, but finished second, behind Minnesota star Adrian Peterson. “I was very, very happy for him.”

In the first quarter, Morris carried the ball nine times for 47 yards, averaging 5.2 yards per rush, but the Redskins still couldn’t put the ball in the end zone.

Dallas broke the scoreless drought with a 13-play, 89-yard drive capped by a Tony Romo touchdown pass to Jason Witten with 8:10 left in the second quarter. Then Shanahan dialed up six rushes on an eight-play drive that featured four Morris carries — the last one the 17-yard touchdown.

In the third quarter, Morris’s production ignited the Redskins and opened up the passing game. Morris carried the ball on five straight plays, before Griffin connected with Garcon on an 18-yard strike down the middle of the field. Two plays later Griffin hit Garcon on a screen for a 10-yard pickup; then he scored on a 10-yard quarterback keeper that put Washington up 14-7.

On the Redskins next possession, Morris scored on a 32-yard run. And with three minutes left and Washington trying to hold off the Cowboys, Morris fought his way across the goal line for a one-yard touchdown that slammed the door on the Cowboys.

“That’s our bread and butter — the running game,” left tackle Trent Williams said. “Any time you have a special back like Alfred, you’ve got to feed him the ball, and you’ve got to let him put his fingerprint on the game. And he did, and had 200 yards rushing, and you can’t ask him to do any more.”