LANDOVER, MD.—Beating Washington looked far from a guarantee for the Dallas Cowboys after their big lead shrunk, but coach Mike McCarthy is plenty confident winning a close game is good for his team. Micah Parsons sacked Taylor Heinicke twice and forced a fumble that was returned for a touchdown, helping the Cowboys make good on McCarthy’s “We’re going to win this game” guarantee by holding on to beat Washington 27–20 Sunday and snap their rival’s winning streak at four. Dallas led 24–0 and 27–8 before Kyle Allen replaced Heinicke and led a 73-yard TD drive and Cole Holcomb intercepted Dak Prescott and ran it back for a pick-6. Washington’s comeback bid came to an end when Allen fumbled with 2:24 remaining. “There’s so much value in those moments,” McCarthy said. “To get where we want to go, we need to thrive in those situations. Now we created some of it …