The Washington Redskins spent the week preparing to keep Tony Romo and the Dallas Cowboys’ offense out of the end zone. They succeeded. But six field goals by Cowboys place kicker Dan Bailey, the Redskins’ own inability to find the end zone, a late-game penalty and a Rex Grossman fumble with 28 seconds left doomed Mike Shanahan and company to an 18-16 defeat at Cowboys Stadium on Monday night.

After holding the Cowboys’ offense in check for nearly the entire game, the Redskins had a chance to clinch the victory as their defense denied Romo and the Cowboys in the red zone with seven minutes left to play.

But rather than move into range for a field goal that would have given them a 19-15 advantage, Washington had to punt. The Cowboys came back with yet another drive that ended in a field goal, putting them ahead by two.

Still, the Redskins had a glimmer of hope, getting the ball back with just less than two minutes left to play. But with his team facing second and 10 from its 43-yard line, Grossman rolled to his left to avoid the rush but was stripped of the ball by Dallas linebacker Anthony Spencer.

“It’s extremely disappointing. We moved the ball pretty decent,” said Grossman, who on the night completed 22 of 37 passes for 250 yards but in addition to the game-sealing fumble, also threw an interception. “We were backed up and we felt like were moving into good position with 48 seconds left, needed about 25 yards to put us in decent range, but couldn’t convert. We’ve got to swallow this one, regroup and get ready for St. Louis.”

The Cowboys recovered and ran out the clock to improve to 2-1 on the year while dropping the Redskins to the same record. Washington suffered its second straight loss to Dallas and dropped to 7-8 against its rival on “Monday Night Football.” With the defeat, the Redskins missed an opportunity to open the season 3-0 for the first time since 2005 and a chance to improve to 2-0 in the division.

“We’ve got to figure out a way to finish out a game,” said tight end Chris Cooley, who recorded four catches for 41 yards. “Offensively, we had a shot. We had the ball with seven minutes left, we had a couple first downs. We’ve got to say, ‘We’re going to win this game and win right now.’ ”

Cooley and the Redskins were outgained 375-298 even as Washington edged Dallas in first downs (20-17). But both teams managed only three successful third-down conversions, and Washington made good on only one of three trips inside the red zone.

“At the end of the day, you either find a way to win, or you don’t,” Shanahan said. “We had some opportunities to win and we didn’t take care of it. The Cowboys found a way to get it done.”

After an ugly first half that featured a total of six field goals by two struggling offenses, it was the Redskins that finally found the end zone in the third quarter.

Stringing together a nine-play, 76-yard drive, Washington took a 16-9 lead when Grossman completed a one-yard touchdown toss to running back Tim Hightower with four minutes left in the third. On that drive, Grossman was a perfect 4-for-4 passing, and Hightower ran the ball for gains of two, 25, six and five yards.

The Redskins couldn’t maintain the momentum, however, and had to punt on the next possession rather than capitalize on yet another strong defensive stand.

Washington dodged a bullet with just less than seven minutes left on the clock, however.

Dallas appeared to find life after getting the ball at its 19-yard line following a Sav Rocca punt, and thanks to a 40-yard run by Felix Jones and a 25-yard pass from Romo to Laurent Robinson, the Cowboys moved into scoring position at Washington’s 10-yard line.

Linebacker Rob Jackson, who entered the game in place of a hobbled Brian Orakpo, drilled Romo from his blind side and forced a fumble, which Dallas recovered. But on the same play, safety Oshiomogho Atogwe was flagged for holding in the end zone. That gave Dallas yet another opportunity as the officials placed the ball at the 2-yard line and awarded the Cowboys another first down.

But former Cowboy Stephen Bowen stuffed Tashard Choice for a three-yard loss, and Romo then threw back-to-back incompletions — the first of which was broken up by cornerback Josh Wilson in the end zone. The second errant throw came in part because of pressure from rookie linebacker Ryan Kerrigan.

Bailey made his fifth field goal of the game to pull his team to 16-15 with 7:01 left.

The Redskins looked to milk the clock and reached the Dallas 49-yard line before losing ground when the Cowboys dropped Grossman for an eight-yard loss. Washington ended up having to punt, but forced the Cowboys into third and 21. Defensive coordinator Jim Haslett dialed up the blitz with eight men on the line, and Romo torched the Redskins for a 30-yard completion to Dez Bryant, with a 15-yard facemask penalty on cornerback DeAngelo Hall tacked on. That pushed the Cowboys into range for Bailey’s deciding field goal.

“Terrible play,” Hall said, expletives flying. “End result was a first down. I told the ref after the game, worst call of the game. He’s going to get some demerit points for that. That wasn’t no first down. . . . But end of the day, you’ve got to keep points off the board, whether it’s touchdowns or field goals, we didn’t do that.”

Although points remained hard to come by in the second half, the final two quarters featured slightly better play than the first two.

The Redskins and Cowboys made their way through an ugly first half that saw both teams struggle to execute on third down. Both offenses turned over the ball deep in their own territory and neither could capitalize in the red zone.

Washington spent the week leading up to the game talking about the importance of finding ways to finish drives with touchdowns. Twice they moved inside Dallas’s 20 but only once did they come away with points.

On the first, LaRon Landry forced a fumble while running down Cowboys wide receiver Kevin Ogletree, and Wilson recovered it on the Dallas 9.

But Washington managed to pick up only one yard in three plays and had to settle for a 27-yard field goal that gave them a 6-3 lead with 21 seconds left in the half, Washington’s second field goal of the game. The first came on a 46-yarder from Graham Gano on the opening drive of the contest.

Dallas, meanwhile, came back with a drive of its own and had to settle for a 27-yard field goal from Bailey. The 9-yard line was the closest that the Redskins came to the end zone in the first half. On their first possession of the second quarter, Grossman threw a pass intended for tight end Fred Davis, who was in double coverage, and Dallas’s Sean Lee picked it off. But like the Redskins, the Cowboys couldn’t capitalize on the turnover, and had to settle for another Bailey field goal — this one from 32 yards out, for a 9-6 lead.Washington’s next two possessions ended in a punt and a blocked 36-yard field goal attempt (the second blocked field goal of the season for the Redskins). The team got the ball back with just more than two minutes left in the half and marched 48 yards in 10 plays to set up Gano’s 50-yard field goal that knotted the score at 9-9 at halftime.