It was the first time the Celtics played at home on Christmas, and they were fighting an uphill battle throughout the game. They wiped out an 11-point third quarter deficit and led by five before the Wizards (19-15) caught fire.
Beal scored 25 points and grabbed eight rebounds, John Wall had 21 points, 14 assists and five boards, Otto Porter Jr. scored 20 points, Oubre posted 16 points and five rebounds off the bench, Markieff Morris had 14 points and seven rebounds and Marcin Gortat 11 points and 10 boards.
Wall moved into fourth place on the team's all-time scoring list and had at least 13 assists for the 24th time this season.
The Wizards controlled the offensive boards and forced the usually sure-handed Celtics (28-9) into numerous fourth-quarter turnovers.
The loss dropped the Celtics to just 5-6 in their last 11 games.
Kyrie Irving and Jayson Tatum led the Celtics with 20 points apiece, Terry Rozier had 16 and 16 rebounds, Al Horford collected 12 points, seven rebounds and six assists and Marcus Smart 10 points. Jaylen Brown had eight points and nine rebounds in the loss.
Last season, the teams played 11 contentious games, including playoffs, the Celtics winning all six and the Wizards all five on their home floors.
Overall, Washington had lost nine straight in Boston.
Boston's Marcus Morris returned after missing nine games with a knee injury. He could miss more during his rehab, but returned and played against his brother. Marcus Morris had two points and four rebounds in 17 minutes off the bench.
NOTES: G Isaiah Thomas, close to returning to action for the Cleveland Cavaliers, criticized the Celtics for misleading him on his hip injury. "If I went back and could do it again, I would've sat out the playoffs, because I would've been playing right now," he told ESPN. "I would've been 100 percent healthy. I do wish I had more information. It was never, this could be something that could possibly shut you down for a while. Because if that were the case, I definitely wouldn't have played." ... Boston G Shane Larkin returned after missing two games with a knee injury. ... Gordon Hayward, expected to miss the season for Boston, addressed the Christmas Day crowd pre-game. ... New England Patriots Rob Gronkowski sat courtside, near the Washington bench. ... The Wizards visit Atlanta and the Celtics are at Charlotte Wednesday night.