IRVING, Texas - Sure, you're probably wondering what this Eagles season could have been like if the team that showed up today at Texas Stadium and three weeks ago against the unbeaten New England Patriots would have shown up during some of those excruciatingly close losses.

The Eagles' players and coaches may be thinking the same thing.

Tonight, however, as they boarded their charter flight back to Philadelphia, the Eagles allowed themselves to smile and enjoy a 10-6 victory over the Dallas Cowboys.

Of course, it should be noted that the Eagles remain mathematically alive for that final playoff spot even though they are a 6-8 team. Dallas slipped to 12-2, but still clinched a first-round playoff bye because Seattle lost to Carolina.

"I've never been so happy scoring 10 points in my life," Eagles offensive coordinator Marty Mornhinweg said.

That's because 10 was enough to hand the Cowboys just their second loss of the season - the other was against the Patriots - and their first against an NFC opponent. The Eagles won on this day with a dominating defensive performance, a gritty effort by embattled quarterback Donovan McNabb and a selfless play by Brian Westbrook that sealed the victory just before the two-minute warning.

Let's start with the defense.

The Eagles became the first team this season to hold the explosive Cowboys to fewer than 300 yards of total offense and without a touchdown.

They did so by holding the Cowboys' vaunted running tandem of Marion Barber and Julius Jones to 37 yards on 14 carries and by applying constant pressure on quarterback Tony Romo, whose 22.2 passer rating was by far the worst of his career. The second worst was last year on Christmas when the Eagles beat the Cowboys in the same stadium. Romo completed just 13 of 36 passes for 214 yards and threw three interceptions.

Defensive end Trent Cole and defensive tackles Mike Patterson and Brodrick Bunkley came through with fourth-quarter sacks as the Eagles clung to a 10-6 lead that had been provided by a 21-yard field goal from David Akers at the start of the final period.

"I thought our D line played tremendous," coach Andy Reid said. "If you get pressure on the quarterback, I don't care who it is, it's tough to play the position. I thought the D line was getting off the ball and making plays."

So was the rest of the defense.

Defensive coordinator Jim Johnson asked cornerback Lito Sheppard to shadow Terrell Owens for the entire day - a detour from the typical coverage plans when Sheppard defends the left side of the field and Sheldon Brown the right.

"He's a good corner that can run and there are not many guys who can really matchup with T.O. in single coverage," Johnson said of Sheppard.

Like the Eagles' entire team, however, Sheppard hasn't been at his best very often this season, mostly because he sprained a knee on opening day and has never completely recovered. With his fingers cut up and his stomach cramping after the game, Sheppard said he felt good in practice leading up to his showdown with his friend T.O., who provided some "good tickets" to today's game for several members of the cornerback's family. Owens made just two catches for 37 yards.

Sheppard seems to always be at his best against the Cowboys, and this game was no exception. With the Eagles trailing by 3-0 late in the first half and Dallas facing a third and 4 from the Philadelphia 40-yard line, Sheppard stepped in front of Owens and came up with his second interception of the year.

The other was also against the Cowboys. In fact, eight of his career 17 interceptions are against Dallas.

His explanation?

"They say there's a hole in the roof here, so God can see American's Team play, but He's watching me, too," Sheppard said.

After Sheppard returned Romo's interception 16 yards to the Dallas 49-yard line, McNabb led the Eagles on their only touchdown drive. The quarterback made the most critical play with his feet when he got his team out of a second-and-13 jam by scrambling up the middle for 28 yards and a first down at the Dallas 12.

Two plays later, he ran again for a first down at the Cowboys' 1-yard line. He finished the drive by finding a wide-open Reggie Brown for a 1-yard touchdown that put the Eagles up by 7-3 at the half.

"They went all-out blitz and I was able to drop back deep because the front line did an excellent job," McNabb said. "It was a great play call by Marty. A lot of this had to do with us eliminating turnovers and mistakes and our defense created some turnovers."

McNabb completed 23 of 41 passes for 208 yards, but he also proved he still can do a lot of damage with his legs by running nine times for 53 yards.

The defensive's second turnover came with 2:50 left in the game after a sack by Bunkley forced Romo into a second-and-18 situation from the Dallas 37. The Cowboys' quarterback tried to find Owens, who was well covered in front by Sheppard.

When Owens tried to make his cut, he slipped and Brian Dawkins was there for the interception.

At that point, the Cowboys still had two time-outs and the two-minute warning on their side, so the Eagles needed a first down. Things looked grim with McNabb facing a third and 9 from his own 46-yard line, but the quarterback found rookie tight end Brent Celek down the middle of the field for a 29-yard completion and a first down at the Cowboys' 25.

"You just have to stay aggressive," Mornhinweg said. "Usually good things happen if you stay aggressive."

On the following play after Celek's huge catch, Westbrook broke free off right tackle and was headed for the end zone when he plopped down at the 1-yard line. He said he was just following tackle Jon Runyan's orders.

"I wanted to help the team win," Westbrook said. "Jon Runyan told me if I got down to the one to just take a knee and when you see that 6-7, 6-8 load behind you, that's what you do."

That's what he did.

And then McNabb knelt three more times and the Eagles left Texas Stadium with an improbable victory.

Now, the Eagles may be wondering what could have been if they could have played this way all season. Tonight, they were just happy that they had beaten the Cowboys.

"You know you'd hear some things that different people in their organization were saying and you felt like they didn't really respect us," Westbrook said. "Sometimes when you don't respect the opponent, you get beat and it turned out that way today."

Contact staff writer Bob Brookover at 215-854-2577 or bbrookover@phillynews.com.