With reserves in the game, Jaron Johnson scored five points during a 7-0 run by Washington that gave the Wizards a 105-99 lead with 1:12 to play.
Milwaukee made just five of 17 shots and turned the ball over six times in the fourth quarter.
The Bucks were without Jabari Parker (knee), Tyler Ennis (shoulder), Miles Plumlee (knee) and Damien Inglis (illness). Washington was missing John Wall (rest), Nene (calf), Alan Anderson (ankle), Jared Dudley (back), Martell Webster (hip) and Garrett Temple (hamstring).
WIZARDS: DeJuan Blair had a double-double with 12 points and 14 rebounds ... Gary Neal added 14 points off the bench ... After turning the ball over 23 times Friday in Philadelphia, the Wizards committed just 14 miscues Saturday.
BUCKS: Chris Copeland scored 16 points with six rebounds over 27 minutes in his preseason debut ... John Henson scored 12 points with 13 rebounds in 18 minutes off the bench. ... Milwaukee hit just 16 of its 28 free-throw attempts.
STAR WATCH: Beal scored 10 of his 18 points in the third quarter ... Giannis Antetokounmpo fought through an illness to score 12 points in 20 minutes for the Bucks.
NOBLE CAUSE: John Wall was excused from Saturday's game to return to Washington to attend to attend the Light the Night Walk. The Wizards point guard attended the fundraiser for the Leukemia and Lymphoma Society in the memory of Damiyah Telemaque-Nelson, who passed away from Burkitt's lymphoma just shy of her sixth birthday last December.
''If we have players that are committed to that kind of stuff, I don't have a problem with sitting a guy to do that in the preseason,'' Wizards coach Randy Wittmann said.
UP NEXT: Milwaukee hosts Minnesota at the Kohl Center in Madison, Wisconsin on Tuesday. Washington visits Miami on Wednesday.