Delle Donne left after the opening minute Sunday and didn't return to the game.
Washington's next game is against the visiting Phoenix Mercury at 11:30 a.m. ET on Wednesday.
The Mystics lead the WNBA at 9-4. Delle Donne, who is currently the top vote-getter for the WNBA All-Star Game later this month, is averaging 15.8 points and 8.2 rebounds per game.