Washington Wizards coach Wes Unseld Jr. entered the NBA's health and safety protocols on Friday.
Assistant coach Pat Delany will assume acting head coaching duties beginning with Saturday's game against Portland.
Unseld Jr., 46, is in his first season as the Wizards' head coach.
Washington is 22-20 this season, sitting third in the Eastern Conference's Southeast Division.
Meanwhile, Boston Celtics guard Marcus Smart has been ruled out of Friday's road game against the Philadelphia 76ers after being placed in the NBA's health and safety protocol.
The game will be the second in a row that Smart has missed. He sat out Boston's 119-100 victory over Indiana on Wednesday after sustaining a bruised thigh 2 days earlier in a 101-98 overtime win versus the Pacers.
Smart, 27, is averaging 11.6 points, 5.3 assists and 4.0 rebounds in 38 games (all starts) this season.
He has chipped in 10.3 points, 4.3 assists and 3.6 rebounds in 487 career games (266 starts) since being selected by Boston with the sixth overall pick of the 2014 NBA Draft.