He went for 25 points and 11 rebounds in a 116-107 Wizards victory on Oct. 27, and 20 points with 14 rebounds in a 115-112 double-overtime win on Oct. 30.
Harrell last scored more than 18 points on Dec. 1 when he posted a season-high 27 points against Minnesota.
Boston comes into Sunday’s matchup with its own leading scorer, Jayson Tatum, ranked 10th in the NBA at 25.2 points per game. Tatum scored 23 and 27 points in the Celtics’ two previous meetings with Washington.
Despite scoring 27 points and flirting with a triple-double at 10 rebounds and seven assists in the Celtics’ 109-105 loss Friday to Portland, Tatum struggled with his shooting.