The Mavericks completed a holiday season road trip having won all three games.
Dallas had a three-point lead when Monta Ellis missed a jump shot, but Blair grabbed the offensive board to maintain possession for the Mavericks. They went on to convert eight free throws the rest of the way -- two by Blair and six by Ellis.
Ellis led the Dallas attack with 25 points and the Mavericks picked up the win despite shooting just 38 percent. Vince Carter added 13 points for Dallas while Jose Calderon had 11 and Brandan Wright had 10. Dirk Nowitzki made just 3-of-14 from the field and was held to nine points.
Washington was led by 22 points from John Wall.