PHILADELPHIA, DEC. 23 -- Led by a defense that made Troy Aikman its sixth quarterback knockout victim in eight weeks, the Philadelphia Eagles defeated the Dallas Cowboys, 17-3, today to regain control over home-field advantage for their seemingly inevitable wild-card playoff showdown against the Washington Redskins.

With a victory next week over the 5-10 Phoenix Cardinals in Tempe, Ariz., the Eagles (9-6) would clinch a playoff game at Veterans Stadium by virtue of a better NFC record than the Redskins (9-6). Philadelphia is 6-2 at the Vet, where 63,895 fans braved daylong rain today for a game that also had playoff implications for the Cowboys (7-8).

Despite the loss, if they beat Atlanta next week, they will join the 1975 Colts as the only teams since the NFL-AFL merger to go from having the league's worst record to making the playoffs. For that to happen Cowboys backup Babe Laufenberg, who was terrorized by the Eagles defense, will have to come up with a better effort than 13 completions in 36 passes for 140 yards and four interceptions.

After being provided a week of predictions, posturing and other bulletin-board material, the Eagles did not find themselves fully prepared for today's game until late Saturday night, when Alan Grant's interception return for a touchdown for the Indianapolis Colts toppled the Redskins.

"We were watching the game at the hotel," quarterback Randall Cunningham said. "When that guy ran into the end zone, guys went into the hallway yelling, naked as jaybirds. That's when I knew we were ready to play -- especially the defense."

Defensive end Clyde Simmons demonstrated his readiness a little less than five minutes into the game, when he body-slammed Aikman to the artificial turf just after Aikman had dumped a pass to running back Emmitt Smith. Aikman landed directly on his right (throwing) shoulder and suffered a separation that ended his season.

Cowboys linebacker Jesse Solomon guaranteed a Dallas victory this past week, and the Eagles gave his comments prominent display. "They came in here predicting a win," Cunningham said indignantly. "That's ridiculous. You don't come to Philadelphia and do that."

Asked about his team's propensity for physical damage, Eagles cornerback Eric Allen said: "Our guys are great at the technique of squeezing guys, then falling on them. That's the way to put a guy out."

But Allen -- a Lilliputian compared to people such as Simmons, Reggie White and Jerome Brown -- managed some damage of his own. With the score 10-3 and 8 1/2 minutes left in the game, he sprinted forward to intercept a down-and-out pass for wide receiver Michael Irvin at the Cowboys 35-yard line. He kept right on going for the first touchdown of his three-year NFL career.

Two plays later, Laufenberg and Irvin tried to go long on Allen. Again he closed on the ball while it was in the air. Again he intercepted -- this time at the Eagles 10.

"You know {Laufenberg} isn't going to throw the ball down the field accurately," Allen said. "Aikman going out changed the whole complexion of their offense. . . . When he went out, I went to Ben {Smith, the Eagles' other cornerback} and said, 'This could be a good day for us.' "

It was a miserable day for Laufenberg, a former Redskins backup who had not played this much since 1988, when he was starting for the San Diego Chargers. In the first quarter, the Cowboys moved the ball to the Eagles 30 and gave it up on downs. In the second, they reached the 19 but got only a 46-yard field goal, and drove to the 15 only to have Laufenberg throw an interception.

Philadelphia took a 7-0 lead in the first quarter on an 18-yard pass from running back Keith Byars to wide receiver Calvin Williams, set up by a 33-yard run by Cunningham. Byars's touchdown pass was his fourth in as many attempts this season.

With the score 7-3 early in the second quarter, Eagles tight end Keith Jackson made an 11-yard reception to the Philadelphia 35, then fumbled. Byars tried to pick up the ball near midfield, but kicked it forward. Williams finally fell on it at the Cowboys 20, completing a 56-yard gain. Roger Ruzek made it 10-3 with a 29-yard field goal.