The Dallas Cowboys are champions again and the Buffalo Bills are the undisputed kings of the Super Bowl flop.

The Cowboys and the Bills both made Super Bowl history Sunday, thanks to two unlikely stars, James Washington and a redeemed Leon Lett.Washington, a backup safety, had a hand in 17 of Dallas' points as they beat the Bills 30-13 and won their second straight NFL title and sent Buffalo to a record fourth straight Super Bowl defeat.

No franchise in the history of American team sports has lost the championship game four straight times.

Emmitt Smith ran for 132 yards and two touchdowns as Dallas became the 10th straight NFC team to win the league's title game by outscoring the Bills 24-0 in the second half after trailing 13-6 at halftime.

But it was Washington who turned the game around as the Cowboys became just the fifth team to win in consecutive years and tied San Francisco and Pittsburgh with four Super Bowl victories.

Washington returned a fumble 46 yards for a touchdown, intercepted a pass in the fourth quarter that led to another score, and forced a first-half fumble that led to a field goal. Both fumbles were by Buffalo's star running back, Thurman Thomas, whose frustration seemed to symbolize the entire team's.

Lett, who has had to endure two notorious gaffes, made the play that turned the game, stripping Thomas of the ball on the third play of the second half with Buffalo holding a 13-6 lead.

Washington, whose interception led to Dallas' first touchdown in last year's 52-17 rout of Buffalo, picked it up and rambled in for the touchdown that tied the game, changed the momentum forever and guaranteed Buffalo its place in NFL history.

Smith and the Dallas defense then took over.

Smith rushed for 61 yards on the next drive, scoring from 15 yards out to give Dallas a 20-13 lead. Lett, Charles Haley, Jim Jeffcoat and Darren Woodson, meanwhile, all made big defensive plays to shut down a Buffalo offense that had rung up 216 yards in the first half.

It was not a great day for Troy Aikman, last year's MVP.

The Dallas quarterback was 19 of 27 for 207 yards, but couldn't get the ball in the end zone in the first half, when Buffalo's Jim Kelly was moving the ball up and down the field with ease, passing for 176 yards before intermissiion. But Kelly finished with just 260 yards on 31 of 50 passing.

Smith, the league's MVP in the regular season, added the Super Bowl MVP award to his collection.

After being held to 41 yards on 10 carries in the first half, he took over after Lett and Washington had combined to tie it and Jeffcoat and Haley had combined on a 13-yard sack of Kelly on Buffalo's next series.

Dallas then got the ball on its own 36 and Smith carried for 9 yards, then ran for 3 yards, then 9,7, 14 and 4. After Aikman hit Daryl Johnston for 3 yards, Johnston dashed 15 yards up the middle on third and three for the score that gave Dallas the lead for good.

Smith scored again from a yard out 5:10 into the fourth quarter after Washington had returned an interception 12 yards to the 34.

Eddie Murray, who had field goals of 41 and 34 yards in the first half, added a 20-yarder with 2:50 left.

The Buffalo offense controlled the first half, piling up 216 yards in taking a 13-6 lead.

But it was the defense that kept the Bills in the game, allowing short plays but nothing long. Dallas, only 1-for-9 on third down attempts, was held to two field goals in the first period after twice getting good field position. The first time came after Kevin Williams returned the opening kickoff 50 yards. The second came on Thomas' fumble at midfield.

Williams' return, to the Buffalo 48, was followed by a 20-yard pass from Aikman to Jay Novacek that put the Cowboys at the 28. But three plays netted just four yards and Murray's 41-yard field goal gave them a 3-0 lead 2:19 into the game. It was the third fastest score in Super Bowl history.

The Bills tied it 2:22 later on Steve Christie's Super Bowl record 54-yard field goal, set up by a 23-yard pass that Thomas caught in the flat and took to the Dallas 39 by slipping past Larry Brown. The previous record kick was 48 yards, shared by Jan Stenerud of Kansas City and Rich Karlis of Denver.

On Buffalo's next possession, Thomas fumbled after taking a shovel pass from Kelly and Woodson recovered at midfield. Smith ran twice for 11 yards then Aikman hit Harper for 24 to the 15.

But again the Buffalo defense stiffened, the key play coming when Marvcus Patton dumped Smith for a 1-yard loss on second-and-4 from the Bills' 9, and Dallas had to settle for Murray's 24-yard field goal that made it 6-3.

Then the Bills took advantage of a Dallas mistake - a running into the kicker penalty on Dallas' Dave Thomas that allowed the Bills to continue a drive that had stalled at the Bills' 41. It ended with Thomas slashing in from 4 yards out at the end of an 80-yard, 17-play drive.

Late in the half, Dallas drove 62 yards from its own 1 to the Buffalo 37.

But Bruce Smith hurried Aikman on a seam pass intended for Harper and Nate Odomes picked it off and returned it 41 yards to the Dallas 47, where Buffalo started with 1:03 left in the half.

The Bills reached the 9, but had to settle for Christie's second field goal, from 28 yards, to go into intermission with a 13-6 lead.