Tiffany Hayes matched a career high with 23 points, and Atlanta dumped Washington, 76-58, on Sunday.
Angel McCoughtry clocked in with 22 points for the Dream, who have won two in a row.
Ivory Latta scored 12 points and Monique Curry added 10 with seven rebounds for the Mystics, whose three-game win streak came to a halt.
Though Washington led by seven after one quarter, poor shooting resulted in just 18 points combined in the second and third periods. Atlanta took advantage, turning that 28-21 deficit into a 60-46 edge heading into the fourth.