* Rookie Morris rushes for 200 yards, three TDs
* Redskins to host Seahawks next Sunday (Adds details, quotes)
By Steve Ginsburg
LANDOVER, Maryland, Dec 30 (Reuters) - The Washington Redskins defeated the Dallas Cowboys 28-18 on Sunday to claim the NFC East crown for the first time since 1999 and deny their bitter rivals a spot in the postseason.
Rookie running back Alfred Morris rushed for 200 yards on 33 carries and three touchdowns, while quarterback Robert Griffin III added a 10-yard TD run to lead Washington.
The Redskins, who opened the season 3-6 but have now won seven straight, will host the Seattle Seahawks (11-5) in the first round of the playoffs next Sunday at FedExField.
"For them to fight for seven weeks to put themselves in this position says a lot about who they are and what level they've played at," said Redskins coach Mike Shanahan.
"You work to get here. There's only one team that's happy at the end of the season and we want to be that team."
Griffin, who played tentatively at times due to a nagging leg injury, completed only nine of 18 passes for 100 yards but rushed for 63 yards on six carries.
"It's safe to say I'm the happiest guy in the room," the quarterback told reporters. "I was nine years old in 1999. I stand before you at 22 and the Redskins are NFC East champions. To me, it's just incredible."
Washington held a commanding 274-100 advantage on the ground, helping to keep Dallas out of the playoffs for a third straight season.
The Cowboys (8-8), who would have won the NFC East and the final playoff berth by beating the Redskins, closed the season with two consecutive losses.
"Obviously this is very disappointing for our team," said Cowboys coach Jason Garrett. "Our effort and determination for this game was awfully good and indicative of what this team has been doing all year long.
"At the end of the day, we did not get the job done."
Morris gave the Redskins a 21-10 fourth-quarter lead with a 32-yard touchdown run, reversing field against the Cowboys' pursuit. The score, with 10:32 left in the game, put the crowd in a party atmosphere not seen at FedExField in a long time.
The revelry was short-lived, however, when the Cowboys cut the lead to 21-18 on a 10-yard touchdown pass from Romo to Kevin Ogletree and a successful two-point conversion toss from Romo to Dwayne Harris.
With three minutes left and Dallas ready to mount a final drive, linebacker Rob Jackson intercepted a Romo pass in the flat intended for DeMarco Murray to seal the Redskins' triumph.
Romo completed 20 of 37 passes for 218 yards and two touchdowns but the 10-year NFL veteran had three interceptions.
"It stings," Romo said of the loss. "I know all of the guys are hurting. You put your heart in this thing for so long. We had to overcome a lot of stuff just to get ourselves in this situation.
"We had a chance. I'm disappointed that we couldn't get the job done."
With the clock winding down, a roughing-the-passer penalty by Jason Hatcher after an unsuccessful third-and-six throw by Griffin gave the Redskins a first and goal at the six.
Morris scored his third touchdown, a one-yard dive, with 1:09 left to put an exclamation point on the victory.
"We definitely believed, all odds we against us," Morris said of the Redskins' late-season surge. "We had faith in each other. We became a selfless team and put ourselves in a playoff situation, taking one win at a time to get to the playoffs.
"We believed in ourselves even if no one else believed in us." (Editing by Gene Cherry)