ARLINGTON, Texas — For all the attention centered on Dallas' December struggles under Tony Romo, there's another key variable that will determine whether the Cowboys reach the playoffs this season.
Dallas' defense continued a dominant preseason in a 20-19 win over the St. Louis Rams Saturday night at Cowboys Stadium.
Through three preseason games, Dallas' first-team defense hasn't allowed a touchdown.
The only points the Cowboys' defensive starters have surrendered have been 55- and 53-yard field goals by St. Louis' Greg Zuerlein.
Including one quarter against Oakland and San Diego, Dallas' defensive starters have been on the field for 58 plays in the preseason, the equivalent of one game.
And they haven't allowed a TD.
Most NFL teams use the third preseason game as a dress rehearsal for the regular season. That's only 10 days away for the Cowboys, who open early with a Sept. 5 game, a Wednesday night, against the defending Super Bowl champion New York Giants.
Based on three preseason games, the defense is ready.
Minus Pro Bowl linebacker DeMarcus Ware and cornerback Mike Jenkins, Dallas' first-team defense played the entire first half Saturday night. The defense was put in three tough spots and still didn't surrender a touchdown.
A 47-yard kickoff return set up Zuerlein's first long field goal.
Kyle Orton's fumble at the Dallas 38-yard line set up the second field goal. Late in the first half, Rams coach Jeff Fisher faked a punt and went for it on fourth down at the 5. And the Rams still didn't reach the end zone.
On the offensive side, Romo and running back DeMarco Murray look regular-season ready. Both played only in the first quarter, when the Cowboys scored 17 points.
Playing without his top two wide receivers — OSU product Dez Bryant and Miles Austin, sitting out with minor injuries, Romo completed 9-of-13 passes for 198 yards, highlighted by 61- and 38-yard touchdown passes to Dwyane Harris.
Former OU standout Murray rushed for 26 yards on five carries and hauled in two receptions for 17 yards. Murray's highlight play was a nifty 10-yard reception that kept the first drive alive. Dallas, though, had to settle for a Dan Bailey field goal following an offensive pass interference penalty and dropped third down pass.
Coming off an outstanding showing in a win over Kansas City, St. Louis quarterback Sam Bradford played the entire first half. The former Heisman winner from Oklahoma never found a rhythm and was sacked twice. Bradford completed 6-of-17 passes for 64 yards.
Dallas plays one of the league's most difficult schedules. This season the NFC East is matched against the AFC North, a division that produced playoff qualifiers Baltimore, Pittsburgh and Cincinnati a year ago.
That's why how Dallas' defense fares could be just as big a factor as Romo and the offense.