IRVING, Texas - Jay Fiedler is back, and so are the Miami Dolphins' playoff hopes.

Fiedler was 14-of-17 with two touchdown passes and a scoring run before halftime, then threw for another score early in the second half, sending the Dolphins past the Dallas Cowboys 40-21 on Thursday.

Chris Chambers had all three TD catches and Jason Taylor returned a fumble 32 yards for another score as the Dolphins scored their most points since getting 49 in the 2002 opener.

Taylor's touchdown broke things open early in the second half, putting the Fiedler-to-Chambers connection on the backburner and letting Ricky Williams take over. The former University of Texas star finished with 104 yards, putting him over 1,000 for the season.

Fiedler threw only three times in the second half, completing two. He was 16-of-20 for 239 yards with no interceptions. Not bad for his first start since Oct. 19.

Fiedler had been out with a sprained left knee, then returned Sunday night, late in the third quarter against Washington with Miami trailing by 13. He guided the Dolphins to their biggest fourth-quarter comeback victory since 1980, then followed it with the impressive rout of the NFL's top-rated defense.

Miami (8-4) is 1 1/2 games behind New England in the AFC East and 1 1/2 games ahead of Denver and Cincinnati for the conference's final wild-card spot.

The Dolphins have won three straight and are 5-1 on the road, the kind of momentum they need considering their history of disastrous Decembers and a schedule that could set them up for another: at New England a week from Sunday, then home against Philadelphia.

The Cowboys (8-4) lost for the third time in six games, making the kind of mistakes that coach Bill Parcells hates most. No one will be immune from criticism as the errors came on offense, defense and special teams.

Quincy Carter was 24-of-40 for 288 yards and two touchdowns, but had three interceptions and the costly fumble. The final pickoff came on his final pass, right in front of the end zone in the final minute.

Dallas fell out of a first-place tie with the Eagles in the NFC East, and out of a four-way tie for the best record in the conference. Plus, the disappointment will linger for 10 days, until the Cowboys play at Philadelphia, and it erases the joy of a 24-20 victory over Carolina that brought tears to Parcells' eyes.

Dallas was hurt by turnovers, penalties and surprising breakdowns by a defense that had allowed the fewest points in the NFL. The Cowboys hadn't given up more than 32 all season; Miami had 30 early in the second half. Williams also became only the second 100-yard runner against Dallas this season.

Williams' third straight 100-yard game gives him 15 since joining Miami, tying Larry Csonka for the most in team history. It's his fourth straight 1,000-yard season and second in a row in Miami, letting him join Csonka as the only Dolphins players to do it more than once.

Fiedler was looking for Chambers from the start, going deep down the left sideline on the first play. Mario Edwards was flagged for pass interference, a 30-yard penalty that left only 37 more yards for a touchdown.

Williams got it close, then Fiedler dove in from the 1 to put the Dolphins ahead 7-0. They made it 10-0 on a 33-yard field goal early in the second quarter and would lead by at least a field goal the rest of the game.

Dallas got touchdowns on its next two drives, both by Richie Anderson, but Fiedler and Chambers answered each time.

The first was a well-thrown 39-yarder, then Chambers made a big stretch to haul in a 6-yarder and barely tapped the tips of his toes while falling out of the back of the end zone with 10 seconds left in the half.

The Cowboys opened the second half with the ball, down just 23-14. But on the third play, Carter dropped back to pass and defensive end Adewale Ogunleye ticked the ball out of his hand.

Taylor scooped it up and ran easily to the end zone, diving in for emphasis. Then Fiedler hit Chambers for a 35-yard scoring stroke and Carter helped Miami score again when an interception by Patrick Surtain led to a 42-yard field goal by Olindo Mare that made it 40-14.

All Dallas could get after that was an 18-yard touchdown pass to Antonio Bryant.